When you get a new gear, put marking compound on it and check the pattern, like a rear gear. You may have to space up, or cut down height, and you may need to shim the cam forward, or backward. I've seen this happen before, and its been misalignment when it happens fast. Any bias in that gear puts a huge load on the gear as it tries to screw the cam out of the block. The last one I saw was an old factory block where the block busing was so worn it has the gear way too low.