Jim
Sorry that I forgot to answer your question about the prop sticking on the shaft. No my prop does not stick on the shaft at all because it came with a brass thrust washer that goes on the shaft before the prop. The washer is tapered on the inside to fit the taper on the shaft and the washer itself does stick on the shaft slightly requiring a light tap with a wrench or piece of wood etc. to knock it loose. My original equipment prop also had a washer with a tapered hole but it had a larger outside diameter and was thicker. Instructions with the Toque-shift said to remove the original washer and instal the brass one which I did. The hub of the Torque-shift has a circle about 1 5/8 inches in diameter and 3/16 in. deep machined into it and the washer fits right into it. I would think that yours should be the same as that part of the hub has nothing to do with the rubber cushioned part. My drive is a Volvo SX
and yours is a Merc Alpha so the setup will be a little different but I'd think that they would still use a thrust washer. Could you be missing that washer? Is the original washer still on the shaft?
As for grouves or wear marks from the springs I can't see any sign of them in my prop. The springs are close to the inner wall of the hub but haven't even worn the blue color off except right at the ends where the are anchored. I have always had 30 or 45lb. springs I wonder if the 15lb ones have so little tension that the centrifical force causes them to rub the wall? Sounds like the spot where the rubbed would be about the center point of the spring.