If you mean breaking the PERS it was done by being somewhat careless.
I've had the head for a little while now and have moved the eyes on occasion without a problem, unlike an unfortunate few who've had theirs break quickly. As a result, I thought I was lucky and got a strong PERS in mine. Nope. I just was VERY careful with it because I was aware of others' misfortunes who weren't forewarned. I got careless when moving the eyes (showing the head to someone), looking from behind instead of watching the eyes to make sure they didn't get pushed too far accidentally. While adjusting the eyes I did look over from the side and noticed one eye wasn't moving, then the other stopped too and the joystick suddenly became much easier to move.
Damn thing broke!
I removed the joystick panel to take a look at the PERS and the joystick ball socket center hinge looked like it would be castable. So I pushed in the eyes from the front until they popped out using a blunt tool wrapped in plastic. I super glued the PERS center hinge back together (it had split in half and without it the joystick is useless) and looked at it to see how I would add to its sculpt to make a stronger casting that would hold up better than the original. Problem is, once I removed the hinge pins (using a push pin) I realized one of the eyes' own hinge wings had snapped off!
I glued it back on to the eye and realized I would have to reinforce that too!
All of this seemed like too much work for right now so I heated up the inside of the head with a blow dryer and reinserted the eyes/PERS. Somehow I was careful not to rebreak the joystick ball socket center hinge again.
For now, I left the joystick panel off so that I could move the eyes without using the joystick. Funny thing is, I have to do this while watching from behind again!
Hopefully, Hot Toys have addressed the Joker PERS failure with a stronger system for the Bruce DX. It definitely is a fragile system, perhaps too fragile for something that's supposed to be moved with a joystick.
I'm going to write Hot Toys to see if they will offer a replacement. If not, I'll look at the PERS again when I have free time and see if I can't reinforce it somehow without really altering it.