hey, so i just signed up to post this reply. i just got the sig 150 and i love it, i started getting sad when i realized that the fire button was deteriorating, it was starting to rattle more and more and starting to get stuck in firing position more and more. so i did the search and came across this discussion, and then i realized what the problem was, the base circle thingy around the button becomes loose and the button gets looser and looser with it, fixing it is really simple, you just tighten the base of the button, the circle around it and then all is well again! phew! hope this gets other people out of the short term depression i was in too!