I just got a used OS 70 FL and when the crank is rotated to when the piston comes up and reaches TDC, the rod is in limbo for several degrees either way until it begins to travel back down. The point where the rod has effect on the piston's movement seems to be very pronounced, almost binding a tad, but I see no marks on the piston or cylinder head. Anyone have any problems like this before with this engine or another one? []