scout drive belt keeps slipping off

I have the VPI Scout and I can't keep the belt from slipping off the platter. The second I turn on the motor it slips off. I've tried talc and that doesn't seem to help much. What's the secret here?
Todd, the belt, or platter aren't rusted are they?

Do you have the Scout Motor assembly spaced out so it is even with the left edge of the Scouts plinth?

Push the belt down to the last groove on the platter, & the motor spindle. For 33 rpm the belt should stay there or move up to the second groove on the platter on it's own once it spins.

Over talc-ing may be an issue also, so try this after wiping most of it off. As this should work?

Are you sure you have a Vpi Scout, as you having too many issues with this table? Check the label on the plinth as I feel you may have received a Vpi "Beastmaster" in error?
Ha, Ha. No seriously it's not as bad as it seems. Actually for 33rpm (top spindle right?) works fine, but the bottom one...Forget it!
Yes the smaller top is the 33rpm spindle, the belt should rest on the lower shoulder of the bottom of the top spindle. The lower larger diameter spindle is for 45rpm. I have never tried the larger, as I use a SDS to switch speeds. I hope this helps???
as audiobugged stated you may have to raise or lower motor to line up with groove on platter,also rather than turning on motor,turn platter slowly by hand,you can also put your hand on top of the belt lightly next to pulley to keep it from jumping off untill it moves to the correct platter groove ,by turning platter slowly by hand you will be able to see why the belts coming off,hope this helps,,