The problem is that the nipple is so close to the pivot point that the lower row of leads provides. If you drop it, the foam pad behind the display compresses with the Force of the accelerated display unit. The unit rotates around the pins along the bottom of the display, and the nipple comes into contact with the rotary switch. Due to the length of the lever arm created, you get a nutcracker effect on the nipple, and POW it breaks off.

The only way to stop it is to use a dense double sided foam pad of the same thickness as the depth of the leads, instead of the low-density foam tape used at the moment. This doesn't compress so much on impact and it MIGHT help, but I'm not really prepared to test my theory.

The problem gets worse if you use a PCB for illumination over the shaft of the rotary switch. Thing to do is remove the switch!!!