Does the TT have ball bearings or bushings. On the EVO it has bearings and on the one I was talking about it was missing a thin washer that rode on the front of the front bearing behind the prop drive washer/flywheel. Without it the drive washer was dragging on the nose of the engine casting and sounded just like the complaint you are making. We found a small diameter thin washer to place in there and all was OK. You might try looking for such a washer around the house. When you had the prop come off the other day, did the drive washer behind it on the shaft also come off? If so, that is probably what is going on. These are VERY close tolerance machines you're dealing with.

Bruce