Quoted from DaveTheTrain:
I wonder if it's the protector?
Probably not. But you really didn't define "incredibly dangerous to dead bounce on it" beyond it just doesn't work. It could be a bad bushing, or even something as simple as the height of the rubber on the flipper. I find the best course of action for things like this is to grab my phone, and film a deadbounce in slow motion. That way I can see the real action and discover where the energy of the ball is going. Don't throw the ball at the flipper, just drop it from the same spot on the playfield over and over to let it deadbounce on its own. The playfiled protector should not be involved with that.