I can roll them by hand, and there's about a half-tooth worth of slack between the two. On the other hand, there is almost no slack between the armature's drive gear and the idler gear, although the idler gear seems rather sloppy on its shaft.
Their relationship is sort of fixed - the motor bolts directly to the truck frame, so there is zero adjustment I can make from the motor side (short of sanding down the motor mounts!), and on the truck side, the height of the worm shaft gear. The only way I can see that the worm shaft gear would be too low is if the worm shaft bearing was severely worn ... and its not - it's a nice snug fit.
If you look at the overall relationships, the drive gear mates with the idler gear which mates with the worm shaft gear. Three gears in a row that all have to mesh perfectly. Doesn't seem like a good design plan to me, but I'm not an engineer, so...
I did put one together and ran it, and it doesn't seem to behave badly, just a lot of slop between those two gears.
I read some articles on here earlier this week about someone who had repaired MANY of these in the past, @Jon G perhaps? I need to hear from someone who has seen many of these and knows if I'm missing something, or that's just normal.
thanks for your feedback!
George
