several questions? And heres my problems. I pulled jc pump out of my hawiian jet cause it started cavitating when i would try to launch boat hard, bad enough i half to back out of it to about half throttle then roll back into it. Its never done this before and kind of came about suddenly? One trip at lake boat was fine, month later took boat out and its been like this every since? There was one thing different tho, the gear oil was leaking past the seal pretty bad. That why i pull to inspect unit condition and measure all the wear? The wear ring to impeller is .030 total, the impeller really looked good no dings in the veins or rub marks any where. Is that wear exceptable? I do have another impeller like new, no measurable wear. But test fitting it and measuring its at .025 to the wear ring. So its tighter and was going to use it but noticed a problem, the hub on the impeller where it butts up against the flange on the shaft is .060 longer which is not allowing the impeller to fit completely through the wear ring like the original one did. And from inside the housing the original had about .020 from the impeller lip to the flanged edge inside the housing. With other impeller thats new/used has about .060 gap to the flanged edge. when looking at it, even tho its tighter than the original i think it wont seal correctly cause of gap and less wear ring contact area.