My PTR91 A3R w/ mag paddle was loose from side to side, just enough so it would not release all mags. The mag locking cam would not depress or bottom out like pushing the mag release button. The problem w/the mag paddle, it was sliding on the ramped mating surface of the push button mechanism. The mag paddle would slide to the left, looking down into the mag well, thus not enough travel for the mag release mechanism to release mag. The paddle would also hit against the back of the installed magazine, not allowing clean release.
I studied the problem a bit then I decided I needed a spacer on the left side of mag paddle, looking down into mag well, rifle upside down. That would keep the paddle from sliding to the left and also stop the paddle from hitting back of magazine. The mag paddle shaft is about 3/16 per eyeballing and comparing to a 3/16 drill bit. Not much room. I then slipped a 3/16 retaining ring onto the left side of the shaft, it grabbed and has held to date. I oiled it w/30wt and it works great. Very solid no play to speak of and the paddle works as well as the button. The paddle also does not hit the back of the installed mags.
This is how it should work, so for less than 50cts and not having to send rifle back I am very pleased w/my fix.