So the magnet moved on the shaft

I have had this happen on a 380c motor too.

[GeeReg]

I had it all apart and that's how I tapped the magnet back down a little. I really had to hit it to get it to move, but everything inside looked normal I guess. I'll have to wait until the spur gets here to see if it's screwed.

I really need to turn down the braking on this thing because that definitely makes sense. The magnet stops, shaft has too much stress put on it by trying to stop the truck, something has to give.

[BrianG]

Since the other end of the rotor was spinning inside there, won't there be a chance that the insulation on the windings got worn away possibly shorting together?

[GeeReg]

I guess, but I tested it with no pinion and it at least seemed to work fine.