I am helping a fellow TT'er change the water pump seal on his '03 yz 450. The bike is now torn down. The pump impeller appears to have too much free-play. With the pump shaft inserted into the drive-gear, the shaft rotates about 15-20 degrees. When we did my kx500 recently, the pump impeller, which has a built-in gear on the end, was only able to be rotated a couple of degrees. Does anyone know if it is a normal condition for a yz to have that much play. We cannot detect any wear on any of the mating surfaces. I would hate to get his bike back together and have something cut loose. Any info would be appreciated. These blue bikes are still a little baffling to me.