buy a cheap spray / spritzer, fill it with IPA, saturate the hairspray before paper toweling it off. You may have to take two passes to get it right. You can get away with a pretty good layer of the the hairspray, so I usually just touch up the bed with a spray between builds and clean after maybe 10 or something…
If it’s under warranty, they almost certainly cannot deny the claim for this or really many bullshit reasons manufacturers say like removing a “warranty void” sticker - which is still covered. You can sue in small claims. Check out the Magnuson Moss Warranty Act should you need to prove your point.