Thanks jinx'd. I use an Aromamizer Supreme tank (tall monster tank) that is quite heavy, and whenever I close the air ring and dial, then twist off top to fill, I probably -- over the last many years - have put stress on the 510 connection (those screws) and the threads eventually wore from that. That's all I can figure. Only one screw is not stripped and all I'm using at the mo'.
I did look up the screw/grubs at one point years ago and thought they were M3's or something, but can't remember now... but will look up a True Value around here somewhere... I usually use Lowe's but I don't recall them carrying small screws like this...
