With the cart running on (jack stands) the belt should be at the top of the engine clutch.
Failure is very rare on factory clutch. Primary (engine clutch)
The secondary clutches wear out the sliding sheave. (inner part of clutch)
You could remove the clutch bolt on the engine and remove the weight and cover assy.
Inspect the thick thrust washer behind the snap ring. These wear out and may get jammed.
Remove the sliding sheave and clean then grease bushing and o-rings.
Make sure the bearing is ok and the spring is factory. There is no reason to tamper with these clutches. It will only run worse or not engage properly. (not climb a hill etc.)
Make sure you have the correct belt. It should fit kinda tight. It should rub on the primary clutch bearing and be at the top of the secondary clutch pulley.