I have an MTH Proto-Sound 1 263e blue comet with a stripped drive gear. I have acquired a replacement gear which I am confident will work with this engine.  However, there seems to be no easy way to remove the old one and replace it with the new one. The two sides of the chassis are permanently attached, and the shaft which is attached to the damaged gear is also attached to a spur gear on the outside of the chassis, holding it in place. Any suggestions for what to do would be greatly appreciated. I've included some images to better illustrate the issue.

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Can either the worm and/or the spur gear be removed on your new set, if so I would drill out the old shaft to removed the old spur gear and then cut the old gear shaft out.

Once the bearing are clear and clean, I would slide the new shaft into place and reinstall the gears.

Otherwise you will have to cut the frame to release the bearing and shaft.

Good luck

Last edited by totrainyard

Totrainyard, I might end up doing that. The only problem is that the gears seem to be permanently attached to the shafts. I have heard that metal gears can be removed from the shaft if you heat them up with a blowtorch, which I unfortunately don't have access to at this time. I tried using a soldering iron instead, but that didn't work. I'll have to find another way to heat them up. Anyway, thank you for the suggestion! 

The early drives on these locos aren't easily replaced.  You have to cut the shaft with a dremel and remove the pieces.  Replacements available from MTH come with the cross shaft, side drive gear and worm driven gear that is secured with a set screw.

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

John, I think that that part is for the version of this engine with an AC motor built into the chassis and with a mechanical E unit. The one I have uses a DC can motor with an electronic E unit in the tender. I'm not sure if it will work. 

Well, you're right, it was the only part number I found for the #263 motor.   Findi ng those gears will likely involve getting MTH to assist you, maybe call Midge and see if she can track it down.

I hate to be a PIA, but have you determined why the gear stripped in the first place?

If not, the new gear might get stripped also.

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

The part you identified is for Std Gauge ProtoDrive motors.  They have both the individual O-gauge worm driven gears and the whole assembly.  Once you replace it with the new version, the worm driven gear will be easily replaceable.  Deb had a bag with those new gear assemblies and there is a part number assigned, but it may not have been posted yet.  Still furloughed, so I can't help with the part number, but Midge can check with Deb if you email her.

As for why it wore out, it's sacrificial so the worm gear on the motor doesn't wear out.  But, it's Chinese brass, so don't pull heavy loads, don't run it in a museum setting and keep it lubricated (not the easiest thing to do).

Roy, I'm not exactly sure what happened, but my theory is that the grease that was on the gears got old and started to harden, thus damaging the gear. When I took the locomotive apart, the motor's worm gear was almost completely submerged in thick grease which had turned green. I've removed almost all of the old grease, and I plan on doing a more thorough cleaning before I put in the new gear, so hopefully this doesn't happen again.  Jon, I had a feeling that the gear I was looking at was for standard gauge. I'm glad I didn't buy it right away! I contacted Midge about this a while ago, but I don't think I ever got a response. I'll definitely contact her again, now that I have a better understanding of what to do.   

As Jon says, that gear is a very common replacement part in many of the tinplate locomotives.  I've done a few of them in both STD and O-gauge.  I haven't seen the locomotive represented here yet, but it does look like you have to cut the old one out as Jon says.

I did that one quite a while ago.  PITA.  I think I had to press it out.  Press gear off new shaft, and press back on.  G

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

@GGG posted:

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

G, thank you for the information. Do you think I could remove the old shaft with a hammer and punch instead? I don't think I have access to a press of any kind.

You tend to deform the frame if you try to press/punch it out without proper support, and due to the design it is difficult to support.  I had better luck cutting it out and then flushing out all the debris.

Sockets and vise.  While I had a lionel press I never used it.  I do all my work with the bench vise and various sockets and broken drill bit to press wheels, and gears.  Punching is not the method to use.  I do use the flywheel and wheel puller that Timko makes, but the internal gear swaps and such are just basic tools and the vise.  C clips and flat steel can be used as spacer if needed.  G

I don't pound things out unless there's no other way.  I do have a press, and I use it for stuff like this is there's a way to brace the surface to avoid bending anything that I don't want bent.  Looking at this one, I'd probably go with Jon's method and chop it out with the Dremel.  Since the replacement doesn't need any pressing, that avoids any possible damage to the motor frame.

OK, dremel it is. It may be a bit of a challenge, since the frame might get in the way, but I'm sure it can be done. G, how much would the replacement part cost?

Thanks to GGG and the parts he provided, I was able to get the engine running perfectly again! I've held off on completely reassembling the engine though, because I just remembered that I need to replace the smoke unit. I talked to Midge about a replacement, and the only one she has at the moment has a brass funnel which does not match the one on my engine. Is it possible to remove the funnels and swap them?

Why do you think you need to replace the smoke unit?  Typically, unless they've run away and cooked the PCB, a simple rebuild is all that's required.

As for removing the funnels, some screw in, some are permanently mounted.  If you have one that's permanently mounted, it was pressed in, and removing it will leave it loose forevermore.

Why do you think you need to replace the smoke unit?  Typically, unless they've run away and cooked the PCB, a simple rebuild is all that's required.

As for removing the funnels, some screw in, some are permanently mounted.  If you have one that's permanently mounted, it was pressed in, and removing it will leave it loose forevermore.

I brought this engine to an authorized service center back in November because there were problems with the sound system. The guy was able to fix it, but he said that the smoke unit also broke. He gave the engine back to me and said he would call me when he found a replacement smoke unit. I decided that, since it's been so long, I should try to fix it on my own. I disconnected the smoke unit and tested it, and I couldn't hear the fan spinning. The funnel on this smoke unit seems to be pressed and glued into place. 

The fan is an easy to replace and cheap as well.

I'm not sure if the fan is the issue. I had just assumed that a component of the circuit board got damaged. 

Unplug the fan from the PCB and use a 1.5V battery to see if it spins.  If not, replace the fan motor.  Next suspect is the LM92 package 5V regulator, those go out most often of components on that board.

PS-1 smoke boards can be repaired.  As long as you did cook the PCB so bad that traces disappeared or burned the fiber.  If you put a picture up, may have the top board assembly.  Worst case is the stack can be removed from the bad PCB if it is damaged.  Swedged and reinstalled in another.  Epoxy is your friend, if really damaged.  Normally though, just rebuild the unit.  I can do it if your not sure what is wrong and some of the electronic parts are damaged.  G

@GGG posted:

PS-1 smoke boards can be repaired.  As long as you did cook the PCB so bad that traces disappeared or burned the fiber.  If you put a picture up, may have the top board assembly.  Worst case is the stack can be removed from the bad PCB if it is damaged.  Swedged and reinstalled in another.  Epoxy is your friend, if really damaged.  Normally though, just rebuild the unit.  I can do it if your not sure what is wrong and some of the electronic parts are damaged.  G

The motor works fine when tested independently of the board, so the board has to be the issue. I can't tell which component

of the board failed, but some of the solder points in the right picture look burned. Maybe that has something to do with it.

 

IMG_4663IMG_4664

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I just read on another post that the 78l05 5v voltage regulator is what usually fails on these smoke units. I think it's the component that I circled in blue. Could that be the problem here?

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