I just got a 2004 fx ho with 210 hours and it is slow to accelerate from a standstill. The top speed is also low at 50mph. I checked the impeller clearance with a flat feeler guage and got .53mm. Service manual says .35-.45 is the spec and .6 is the max clearance. I did not see or feel and ridges or imperfections on the stainless steal wear housing around the impeller. Is it possible that the impeller wore down without the metal wear ring becoming worn?