I wouldn't recommend taking it apart, as it will not go back together (don't ask how i know

). Is the button sticking? If it is, I would recommend pulling the the center post and find a friend with an ultrasonic cleaner. Running it through a few cycles (Hornaday makes an excellent one, but it's way to expensive clean a few mods with) will usually remove any junk clogging smooth operation, if the problem is more serious (bad machining) try working some graphite powder down between the locking ring and button. Work that stuff in, then clean it again. the graphite is usually super fine, and seems to smooth out sharp edges. If all else fails i would recommend buying a new one, then experiment on the old one. And if you can find a way to remove it without damaging it, please let me know. If it's misfiring the issue is more likely having to do with the center pin not making good contact with your atty, but thankfully the 20v3 has an adjustable center pin to clear that up.