Need MPC Repair Help

If your idler gear is plastic, I believe the part number is 8010-117. Lionel calls it a pinion gear. It rotates on a dowl pin that is pressed into the side of the truck.

I would guess that the gear wore out. I have seen those gears with the hole in the center enlarged. Yours may have become enlarged enough to allow the gear to fall off the pin.

The truck is held to the motor by a single screw through the bottom.

The truck sideframes are mounted to a plate that is held to the top of the truck by a single screw.

It may not be necessary to completely remove the wheel, but I believe it has to be moved far enough to allow the gear to slip onto the dowel pin behind it.

You can download the Lionel manual at the following link. You want Supplement 1-9, around page 416.

http://www.lionel.com/Customer...e/service-documents/

Joe, if it is the middle gear that is stripped, you can either buy just the gear and press it on the shaft, which is driven by the gear on the motor. If it is the gear that actually drives from the middle gear to the geared driver, then CW is correct. If it is the middle gear, disassemble the truck as he suggested, you can buy a gear to press on the end of the shaft. Lionel has used the same shaft and gear assembly from the postwar Geeps, up through to the FT's made by Lionel. 

You can also buy the center gear / axle / worm wheel as a replacement assembly. I have seem some of MPC engines with that assembly put together in a fashion that causes the gears to rub against the truck block. I fix them by either adjusting the spacing of the gears, or by adding nylon washers (requires removing the gears).

In addition the early MPC parts have a plastic end gear, which sometimes cracks and comes off.

The replacements available today might be made better. No special tools are needed to replace this assembly. You will need to save and resuse one of the bearings (see diagram). Or you could buy the bearing too,

Thanks for your advice,

X2000