It's the small cover that goes over the starter gears. For some odd reason I just cant get the cover to go flush with the main case. Top part of cover is flush but bottom half sticks out about a 1/8" inch. Any idea what is holding the cover up? I know it is not the gears because I tried putting the cover on with just the metal pegs that the gears go on and it still won't line up right. Only thing I can think of is somehow the starter was tweaked out of place and maybe I need to loosen it?