mine was doing that and i found ONE of the idler pulleys' lips had the slightest bend and of course it's where the 90° belt guide/keeper is so when it threw it it chewed it in two every time..... I'd put the new belt on with deck off and sit where the pto clutch pulley would be and hold it tight and rotate the belt and see how it's "riding" in the pulley system.
What brand belt are you using and what does the manual say about adjusting the belt tension?
#4
Cusser
My LT1000 917.3888020 was doing this, fixed when I adjusted the deck angle front to back as called for in owner's manual. Somehow that had gotten off-angle after 14 years.
