Will any bad things happen if I run without the mainshaft spacer washer and only the thrust washer? This is the only way I can get my gear clearance right, nothing else has worked. The shaft is just sitting up too high.

 

it'll probably be fine. it's not much of a difference. but, you should see what's causing the mainshaft to sit high...is the bearing not seated fully, or you might have marrs on the mainshaft.