I'm trying to help a friend with his Mule 4010. It won't drive up even the slightest hill and there is an awful sound from within the big plastic clutch housing -- like a bag of hammers is rattling around in there -- so I took off the cover and noticed the belt was so loose that I can remove it without any effort. He bought a brand need belt (shown) from the local Kawi dealer but it did not solve the issue. I have a John Deere Gator (similar drivetrain) and the belt is way tighter and sits much higher on the clutch. Also, I can push/pull the rear clutch housing slightly in a in-out fashion but don't know if that is normal or not.

Any ideas?