I had the exact same problem when I did mine. Mine hit on the piece that is thin and completes the hole for the started (the side of the hole that the engine is on) and another spot on the same side but toward the bottom. The best thing to do would be to take some machinist dye on the inside of the bell-housing to find out where it is scraping and grind it down with a carbide cutter. Make sure you spray WD40 or similar on what you are cutting or the aluminum will clog up the carbide bit.