<VV> belt problem

[GYoungwolf at aol.com]

I've got a call yesterday about a car which throws a belt a minute. It's a 
'65 140 (with the secondary carb ports blocked off), but the engine has a solid 
crank pulley. The belt guards are in place. The owner has tried most all types 
of belts. I'm trying to help troubleshoot over the phone, so I'm not able to 
watch it. The owner says everything appears to be aligned okay. Any 
suggestions? Would the spring loaded pulley solve this?
Thanks,
The Carbmeister