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I have  couple Marx 999 locomotives that are stuck in one direction, in this case reverse.  I have tried spraying with contact cleaner and moving the little wire that swings in two directions.  I do not believe I can get to the eUnit without pulling the wheels and sides of the motor which is a non starter for me.

Any help or suggestions on how to get the reverse to work?



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Not sure if your motor is early or late. Note the hole above the front wheel. If yours is like this, flood the e-unit through the hole, then shake up and down to try and loosen the piston, rinse well, then repeat a few times. Hopefully that will loosen it up. If that fails, you can jam that to forward to lock it in forward. I use a piece of wooden skewer pushed in at an angle to jam the rod.




Images (1)
  • motor

Thanks for the replies Papa and GeneH.

I have tried contact cleaners but maybe not enough or the right one.  I will give your suggestions a try on the two motors.  I have some Caig DeoxIT Fader cleaner and Faderlube I normally only use on stereo equipment as it is pricey stuff but I may have to give it a shot.  I have been using CRC contact cleaner but not drowning the plunger.


I have tried drowning it Caig DeoxIT and working the pendulum pin in both directions.  Mine has the holes in the side of the motor to get a little access.  The piston is free and the pendulum works in the reverse position and swings to the forward position.  About 9 volts were on one brush when running in reverse and no voltage when I force the pendulum to forward with a match stick.  The pendulum is not making contact in forward and that is the cause of it not working.  This is the same problem for both motors.

These two motors are in excellent shape and show no gear wear, etc. and look newer and better than any of my other 5 or 6, 999s or 666s.  The fact they only work in reverse is the reason!  To bad it is not stuck in forward as I could live with that and run it forward and neutral.  I may have to make them Cab Forward engines to get to use them!

Any other ideas out there?




Thank you for the responses and the efforts you made to include the references on how others have worked on this issue.  Ironically, I had just found the internet posts by David Farquhar, from The Silicon Underground site, in which he describes how to remove the e unit from a Marx 999 motor.

I have reviewed the Youtube videos you posted  and others by Benz Trainz.  I now understand how the swinging brass rod throws the two way e unit switch and where the contacts are.  I have worked the e units on both of my motors, sprayed again with Caig DeoxIT strong contact cleaner and neither of them will work in forward.

From Benz Trainz I found that I would have to force remove the e unit from the motor per David Farquhar.   Then to get to the contacts to clean if possible, I would have tear apart the e unit per Benz Trains video.  The contacts may not be repairable.

So I have decided to take the e unit out of the circuit per a sister video by Benz Trainsz and make the engines as forward only locomotives.  I will have to review the video again and make notes as to what wires to remove and which ones to hook up to get to forward only.  I would do better if he had just made a marked up diagram or two of the motor showing which wires to cut and to solder and where.

Pictures for The Silicone Underground by David Farquhar

Fuzzy picture of the two position switch of a Marx e unit from a Marx 999 motor, Bright copper parts are the wiper arms


Dirty contacts of two position switch moving part


Clean moving part of the two position switch




Images (3)
  • Marx_Reverse_Pivot
  • Marx_Reverse_Internals
  • Marx_Reverse_Pivot_Cleaned
Last edited by Choo Choo Charlie

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