Re: UV777BK pickup height issue
One of two things could have happened.
1) simplest - it's possible that the pickup has just been backed out SO far that the screw disengaged - can you pull the screw free with little pressure? If so, then this is a simple matter of popping out the trem, unscrewing the pickguard, flipping it over, and re-seating the screw into the pickup and tightening it back up.
2) harder - the pickup may be stripped out. Couple tings you could do, either repleave it with a screw one size larger that will bite in the pickup, or possibly just lining the center of the thing with a semi-soft epoxy or even just a bit of hard wax (sealing wax might work well, actually), and then threading the screw through while it was still a bit soft, to kind of re-create the threading inside the pickup.
Of course, if you're not 100% happy with the sound of the pickup, this might be a good opportunity to just bite the bullet and try something else.
How did this happen? Did something push down on the pickup hard? Were you lowering it and it just fell loose?