If your belt is too long you can adjust the motor position. There is a screw that holds the motor up. The screw head faces the front of the machine and can be found lower than and behind the handwheel. You can loosen the screw and the motor will drop. You just want it tight enough that the belt grips but you don't want a lot of tension on the belt. It should not be tight, just enough tension to get the belt to grip, if I understand correctly. I had my LSMG put mine on and he adjusted it for me.