I had a similar problem with mine when I first installed it. Make sure there is no twist as you place it around the platter. If you roll it down it may create this problem. Try to stretch it around without contacting the platter. This worked for me.
Belt slipping off Scout
How do you keep the belt on the Scout from moving it's way up and off the pulley. Is it too loose/tight? Pulley too high/low? Talc or no talc.
I'm using the 300 rpm motor.
I'm using the 300 rpm motor.