The bars are held in place by two screws. One on the headband, and one inside the cup (you'll have to peel off a plastic sticker covering it). Take those out and the associated plastic bits and just remember how it all goes back together at the end. You increase the friction by tightening the headband screw.
Whether or not this disrupts the mad dog mods or the warranty, I do not know.
It is a friction assembly, so if you paint the sliders the paint is going to get shredded and look instantly awful. I'm not sure but I think these are an anodized aluminum, not powder coated. You'd probably have to talk to a shop to make sure they can be safely powder coated, and be aware that a thick coat or a rough coat may ruin the slider.
Obviously I won't warranty anything a user does to modify the phone, so if your driver failed (none ever has) I'd repair it, but if the mechanical assembly has problems or you ruin the tuning by opening the phone (very easy to mess up) I'd charge to repair.
I don't encourage opening the phones up; it's possible to break the lead wires or mess up the tuning if you don't put it back exactly correctly.