I fitted a new Wosp hi torque starter motor that I bought last year. The engine is still out of the car and I wired it up directly to a battery. It turns the engine fine but upon disconnecting it does not fully disengage. As far as I can see this is being caused by the starter cogs sticking on the flywheel cogs in the upper edge - ie the spring in the starter under tension and jamming it. There is plenty of room between the cogs. I tried a couple of washers at the bolts, with no effect. Trouble is it is doing the same with the old original starter. The backplate is a new aluminium one (I went a bit over the top last year with new parts). I wonder if the bolt holes are a bit tight and should I drill them out a fraction, which might not any difference. Is there any other explanation for this? (I can't get the cursor to move to make paragraphs).