Tilt machine back, take off belt, and grab the pump. Turn it, if it is rough replace pump. If you have seen a few of them (or hundreds lol), you can tell just by looking at it. I would also look at the belt, usually the belt gets badly worn in these situations and should be changed also. Also, look and check the motor pulley. It is plastic. Sometimes, it starts to melt. Problem is, if you look that up it defaults to the whole motor. It may be possible to still get just the motor pulley, haven't checked in a while.