Well FWIW lowrange, I'm very much into Jetskis/Waverunners and jetboats. We had a Baja Splash jet boat a while back that had a Merc 90hp in it (just a li'l guy) and towards the end of it's useful life we started having the same problem. We leaned towards something to do with the impeller/driveline going out but never figured it out exactly. One of my brothers was driving it under influence one night, left the drain plugs loose in the hull, and it ended up grenading the motor so needless to say, the impeller problems became the least of our worries. Anyway, I hope you have good luck finding that ring for cheaper than what you have so far.