I have a 50s Clark with all-contactor drive circuits. It worked fine, you could put the directional stick in forward or reverse and it would go that direction until you hit the brake. All good. Then I made the mistake of washing 50 years of grease out from the inside, now I have an issue with the movement contactors.

If I try to go forward with the directional stick, I have to reach down (with an insulated screwdriver) and push the relevant contactor manually. It then sticks and drives as normal. I hit the brakes, it drops the contactor and stops moving.

I'm assuming something is wrong with the coil, but forward and reverse seem like they're mostly separate, so I'm confused why both stop working at the same time. I'm guessing there's an interlock that prevents one firing when the other does, but I'm not sure.

I did pull a couple wires off the traction motor to clean up the contacts, but they went back on the same studs. And it rolls fine once I manually connect the contactor pads.

Any ideas for troubleshooting this, or a better wiring diagram than the one inside the cover that I can't read anymore?

S/N 14EA189