Cut down some 1/2" plywood and it cut like a dream. Same with 3/4" mdf. Now I'm cutting 3/4" plywood and I'm burning the edges (a lot!) and it stalls out. Cleaned the blade several times and it looks pretty good. What could be going on? I know mdf dulls blades but this is ridiculous. It's sliding fine on the rails, kerf doesn't seem to be closing up.