The plastic handles for hot and cold on my tub faucet work perfectly except for falling off occasionally because the screws that used to hold them onto the stems have rusted away and have no heads. I might be able to use a screw extractor to remove what's left of the rusted screws, but they're so small, it seems more difficult than just applying something sticky to the brass splines so that the handles will come off only if deliberately pulled. Any suggestions on something that would remain sticky but not harden into a permanent glue?