Hi mini gurus
After a bit of gearbox building advice as I'm rebuilding mine again
It seems every time I try to run inchups I'm certain to blow the gearbox.
This time I'm using the reinforced gear set but I think there is another problem. Perhaps a misalignment of the shafts in the chassis? I purchased the bearings of m chassis so I'm pretty sure they are correct, but they are loose in the gears?
I'm also finding that when the motor is out all seems well. As soon as I tighten the motor screws it seems to bind. To get around this I run the screws very lightly tightened. But the slightest bump shifts the motor and strips the spur. It all seems worse after replacing the chassis. Any insight would be greatly appreciated

Mick