Quoted from Radiowing:
Yes, let us know how it goes, BlackRabbit. I took a look for sagging in my hand mechanism and could not find anything that I felt I could safely "bend" out. However, I did experiment with letting the matrix sag down by loosening it from the back board at bit. If it worked, my plan was to shim it and then re-tighten it. No dice, though. It still picked up two balls in multi-player mode. I like having 2 balls, but not Johhny's glove.
Radio. I just finished tinkering (without new parts). I hand placed two balls in the matrix at many different positions. With the game on and glass off as soon as I did this the hand march over to pick a ball. This was good since it saved me tons of time messing with the switch and test menus. Anyway, as soon as the hand reach the matrix I quickly reached in and used a finger to lift the hand. I have play at the x and y but I discovered. With this play removed or compensated for by my finger, the magnet only picked up one ball. It appears the distance between matrix and hand is very important and sensitive...on my pin anyway.
I am confident finally that I will resolve this. It all makes sense now. Played perfect for two years then started picking up two balls likely because hand sagged and is now close to matrix which allows the magnetic field to influence/grab near by balls. What caused the hand sag? I think folks here in this thread nailed it. X and y nut wear (friction between but and turn screw). Then the hand has shake or play and sits lower. In addition, like said here, gravity!!! The game, even when idle, has gravity pulling on that heavy hand mass 24 hours/day 7 days/week! Hand sags more. Too bad the engineers did not counter balance that mechanism load or even add an assist spring to help fight the gravitational pull downward.
Oh well. I feel pretty good that when my new y and x but goes in with also some gentle tugs upward to counter the sag, it will work properly again. I will update here either way though.
Thanks for all the great tips everyone!