I have a Craftsman riding lawnmower that has the type of clutch that operates by releasing tension on the drive belt via a moving pulley when the pedal is pushed in.  I recently performed some maintenance on this mower by replacing the drive belt and the worn-out moving and stationary pulleys.  Ever since I have done this, however, the transmission (manual 6-speed) is frequently very difficult to shift.  Sometimes to get it to go into reverse, I have to get the mower rolling forward while shifting, and sometimes have to get it rolling backward to shft into forward.  When it gets really stuck, I have to turn the mower off, and then it shifts easily.  When looking under the mower, I can see that when the clutch pedal is pushed in, the pulley on top of the transmission is still rotating at a pretty good clip.  Shouldn't that pulley come to a near stop or at least a slow rotation when the clutch is in?  When I changed the belt, I used a PIX belt that was supposed to be the correct one for my mower.  I'm wondering now if maybe that belt was too small - that maybe I should have used an OEM belt.  It seems like there is too much tension in this belt - what do you'all think?