I have a 93 ProStar that has always had some vibration. The coupler gap was checked a few years back, and I have added a 4 blade. It runs pretty smooth compared to other like Mastercrafts. The packing is origional, and the raw water pump new, and vibration free. No play in the strut. 700 hours. Any tips out there on fine-tuning this to a little less vibration.