Is there a trick I'm not aware of to getting the needles back into the carburetor, the low-end needle especially, without damaging the o-rings? I don't know if it's due to their age because the engine's quite old (RX21R1WC), but it seems like I'm tearing them slightly the last couple of times I've taken the carb apart, even after soaking them in very light oil or coating them with green slime.