129 pto deck belt probs
 

Got a 129 with a 42 square end deck that when I run it for a bit the belt almost always ends up upside down on the pro pulley.

Any suggestions? What to look for?

How does your belt alignment look? Belt tension? Are your pulley surfaces/grooves straight, rust-free, and function correctly?
Are you running a good belt? A genuine Cub Cadet belt for example.

http://www.onlycubcadets.net/forum/showthread.php?t=5