Marx 1666 locomotive - Opening a can of worms?

To start, remove the brush plate (the two nuts and the screw).  This will allow the brushes to come out and give you access to the commutator.  Clean the commutator and brush wells with rubbing alcohol and swabs.

Also clean any debris you may find inside.

Use electronic spray cleaner and give the reverse unit a couple of shots.

Clean all the wheels with swabs and rubbing alcohol.

Lightly sand the pick up shoe on the bottom and clean with alcohol as well.

Re-assemble, cross fingers...........and try it.

All the best

Dave

Everything Dave mentioned!!!! From my own personal experince and looking at your motor, there's only one wire to the brushes, so the other brush without the wire goes to ground. Some Marx engines use a simple washer to make the ground connection from the bottom screw to the brush holder without the wire.  On the Marx motor I was working on, someone left out the washer and the armature circuit was open and all the motor would do is buzz, just like yours. I discovered it by making the ground connection with a screwdriver accidentally. Check to see if the washer is present under the screw and it overlaps enough to touch the bottom brush plate. Good Luck! hope this helps.

Ed Horan

If you can't get it working, I have just the person to send it to: Bob Testa, aka Marxmotorman. He's saved more than a few of my (often self-created!) basket cases, and IMHO does it more for the love of the work, rather than financial incentive. Here's one of his videos:

If you need his email as well, let me know, and I'll send it to you.

I've seen worse, do what Dave said and don't forget to clean the collector as well. Also clean the brushes themselves or better yet just replace them. Marx motors are bullet proof, have faith it will run again.  let us know how you make out.