What we have found is anytime you R&R the belt you must make sure the bolt bottoms out. You can torque the bolt to specs but if the belt is too low in the clutch it will give you a false tightening effect. The belt will hold the clutch open. When you intially tighten the bolt it will bottom out, then turn the belt so it rides/slides/slips over the clutch. Sometimes it's hard to get the belt to turn because it is jammed in there by the bolt. Then retighten the bolt to specs, it almost always will turn a few more turns.
We found this works perfectly, before we did this religiously we had the bolt come loose sometimes days after we did belt work.