Quoted from mrgregb123:Correct, except you can in fact add whatever nonsense you want. The manufacturer still has to show that the defect you are reporting was caused specifically by your mod(s), and the remainder of the warranty remains intact. Manufacturers try hard to convince users otherwise and blatantly lie to you ("Opening this [whatever] will void the warranty") but the law is the law.
Here's how that will go, every single time...
Buyer: "Hi, my game won't turn on. I need a new power supply."
Stern: "We're really sorry to hear that. Did you modify or alter you machine in any way from factory?"
Owner: "Not really, I just added a doll that taps into the power supply."
Stern: "Ok, then No."
Buyer: "But that's not what caused it. It's from a reputable modder who's well known in the industry for making quality mods that tons of pinball owners use all the time, without issue."
Stern: "No."
Buyer: "Well, the law says I'm allowed to do that and you still have to honor the warranty."
Stern: "Yeah, No."
Buyer: "I can sue you, and at least certainly never buy another product from you guys ever again!"
Stern: "Still, No. Though if you'd like to purchase another Power Supply, please visit one of our authorized retailer's websites. Thank you for being a Stern customer. Goodbye."