by gascarnut » Thu Jan 31, 2013 4:53 pm
If the pinion is a slide fit onto the motor shaft, I would use red Loctite rather than solder. Just make sure everything is clean and apply the Loctitie to the pinion, not to the shaft so it gets pushed deeper into the pinon when you install it.
I would agree with leaving the original wheels and gear in place unless the gear is completely bust and it does not look that way. Get some replacement tires, though, and true the whole assembly (you do have a Tire Razor or an Area 3, right?). IMO, you want always to retrian as much of the original as possible.
if the guide itself is still good, but does not stay in place, then put a little o-ring around the top of the shaft where it protrudes through the frame.