Mercury jet boat pump parts for sale for 1996 120 hp Sugar Sands?

I am having problems with my1996 120 hp mercury jet pump. It cavates badly, thumps and clunks.The bottom intake plate has loosened up a couple of times elongating the screw holes. I have previously sucked up a couple of ski ropes. I have owned this boat since new and have not abused it. I had the wear ring replaced with no noticeable improvement. I would like to find a compleate pump to replace it. Any help would be appreciated.|||http://motors.search.ebay.com/?from=R40%26amp;鈥?/a>