Second, I would have to know which part was "loose."
Third, I would have to know what part you "unscrewed" part way and then screwed back in.
what?
I still don't understand.
so was the house that holds the laser diode moving when you tried to turn the lens?
well if that was true. then the laser module was lose.
This is due to that set screw on the heatsink.
So before u used it you put it back and tightened that screw or what?