hi everyone. I have a 1990 murray tractor that im having issues with. the problem is that when climbing a hill or pulling a load in high gear (4th-5th) my drive belt is slipping. I replaced the belt with a Kevlar correct size belt. the tension is good and the clutch is adjusted also. It seems the pulley on the trans is not made with a V groove like the crank pulley and that is where the slipping is happening. is this normal for the safety of the trans under loads? the pulley on the trans is just a square groove which seems like the belt fits loosely and wouldn't be able to grip it.... any suggestions?