We seem to be having on=going problems with our 310 in relation to the prop shaft and possibly engine alignment. At reccommended cruising revs of about 2100 to 2500 rpm we get an unacceptable amount of noise and vibration. The dealer replaced the prop shaft with a stainless steel one and balanced the prop as well as aligning the prop shaft (the original shaft was damaged when a PSS shaft seal was fitted). The shaft seems to move about a bit relative to the shaft seal which by the way is leaking constantly spraying a small amount of water (I have cheched the adjustment of the seal several times). I suspect that the engine/shaft alignment might be out. Has anyone else had similar problems? Any advice would be most welcome. I'm also thinking of a 3 blade prop to replace the standard 15x10 two blade as a way of cutting down noise and vibration as we are doing a reasonable amount of motoring