The smoke unit can be rebuilt but you have to "unpeen" the front of the smoke unit to remove the fiber disk. Doug Peck (Portlines Hobby Supplies) has the rebuild kit (ID:1669 - $8.95). The kit is also available on eBay for $10.00 and $3.00 shipping (seller "littlesteamers"). Make sure you don't pay 20 or 30 bucks from rfgco.
Here is the blurb from Doug Peck's "repair clinic":
II. FRANKLIN, DOCKSIDER, & GILBERT-HO ENGINE SMOKE UNITS
These smaller smoke units are constructed very differently.
To rebuild these units,
1.) Unsolder the lead on the front of the smoke unit chamber which connects to the edge of the chamber ("ground").
2.) File away, or "unpeen" the front edge of the chamber.
3.) Now the front disk will pull out of the chamber. You will note that this unit has what looks like a wirewound resistor attached to the front disk; this is the heater element. Inside the chamber should be some wadded wick material which absorbs fluid and keeps it in contact with the heater element. However, I have encountered many of these units with no absorbent material at all, which explains poor smoke production.
4.) If the disk is undamaged, you can clear the solder from the two holes, and replace the heater element( which we supply with a fiber sleeve around it). Test insertion to be sure the wire lead at the rear end does not contact the back of the chamber. (If you can't avoid that lead touching the chamber body, then just be sure that lead is the one that gets soldered to the edge of the body in step 7 below.)
If the disk is damaged, then you will have to salvage one from another unit, or make a replacement from something like circuit-board material.
5.) Disk is reinserted, with some soft wick material loosely wrapped around it, if you have any available. Don't wrap it tightly, however, so it doesn't burn.
6.) Seal the edge with epoxy, or JB Weld.
7.) Bend the shorter lead (the one from the piston end of the smoke chamber) over, and solder it to the edge of the chamber, like the original [this = ground]. (Be sure you do this with the correct lead….otherwise you can create a short.)
Note that Doug's kits and the littlesteamers kits (they are the same) include a new fiber disk. I've done the repair and it's not difficult. Be careful not to remove too much material when "unpeening) the front edge of the chamber as the element and wick are already a tight fit in the chamber.
NOTE: Lionel sells a complete smoke unit (for Docksiders - 6408039200) for $18.50. It is listed as 18ohm. It would be a nice, easy replacement for the Franklin but I think the Lionel Docksiders have regulated smoke voltage, so some modifications might be required for a retrofit. Retapping the mounting screw holes might also be required. I purchased a couple of the Lionel smoke units just before I discovered Doug Peck's replacements so I never got around to trying the conversion. If anyone has tried it I'd be interested in hearing the results.