I just replaced the upper gear case bearings and unfronze shifter cable that was stuck and replaced water pump in my 1979 OMC 800 outdrive w/350 Chevy, 260 hp. It will shift into reverse ok but shifting into forword it grinds. Acts like it is not sychanizing. I took it apart and tryed adjusting shifting cables to meet measurements from the book. It still grinds into gear. It seems to do it worse when the prop is on. This Pursuit has been setting for about 2 years. The engine runs great. Can you give me some ideas on how to fix the grinding.