On the table is the original motor mount that shipped with the Mini-T, which offers only 9 possible gear mesh settings. For better performance, this was replaced by an aftermarket motor mount that allows for more precise gear mesh adjustment, and thus creates better mechanical transfer between the spur gear and the pinion.

On a side note, if you don't have the correct wrench or your sockets are too big for the Mini-T, you can easily tighten the slip clutch nut (located left of the motor pinion) by using a crescent wrench as you gently pull the Mini-T backwards on carpet. You'll know you've got the correct tension once the back tires start to give resistance.