snapper mower stalls

[mallyn5.0]

I have a snapper 12.5hp 28inch cut rear engine riding mower. When i start the mower and put it in a forward gear and let out on the clutch/brake peddle, the mower tries to shut down unless i push the peddle back down. But when i put it into reverse it moves fine. I have noticed that when going from the reverse gear to a forward gear it feels like the clutch is not ingaging correctly.

 

[Rivets]

Sounds like the belt is grabbing. When was it changed last? Grab the shift lever while you are letting up on the clutch, do you feel the tranie engaging in a gear?