If they are in violation of the MMA go contact a class action attorney and ask if you have a case. It would be a juicy pay day for that law firm lawyers dream of cases like that.

The MMA explicitly says a class action is an appropriate remedy so pursue it. Until then you can winge about the act all you want but until you take action that law means nothing. Until someone sues that law is meaningless and toothless.

Same with your silly example - I do some work on my transmission, if Ford can't prove that my work caused damage to the engine, they warranty it.

This isn't my example. Someone compared guns to cars and I responded. I'm simply trying to point out that guns and cars are fundamentally different especially if you're comparing repairs. It is literally apples and potatoes not even oranges.