The locktite worked! I tightened up the one closest to the strap pin and put locktite on it and left the other adjustable. If you tighten the front one up too much you can't move the arm around. Sorry it took me so long to get back to the board. I ended up buying another ZT3 and locktited it as well. The arm is nice and solid now.
I have the same problem but I am going to try some locktite on the screws. The one closest to the bottom of the guitar I have tightened up as far as possible. The one closest to the neck I adjust until the arm is solid enough but I can still swing it into the locked position. When I have tried the locktite I'll let you know how I go.