Quoted from Rob_G:
The gap requirement leaves very little room for error. Mine 'stick' too, but for now they are working so I will leave them alone. I am hesitant to use any threadlock, but may have to if the hex shafts keep coming loose. Then I will only use a tiny bit of blue threadlock.
I used blue threadlock on mine. Haven't had to even touch the ball switches in 1200 or so games since I did that. They work perfectly and the game's a lot more fun.