At the 2020 Southwest gathering, cap seal replacement came up and having a couple that needed replacing I polled the group for tips. One that came up was torching the seal. This suggestion came with the additional information that it would work but you would destroy the paint. So as I was picking the stubborn seal on a one piece cap I got to thinking what might get the cap hot enough to help break down the seal without damaging the paint. After way too long picking at the seal, I set the cap on the vent nut of a lit lantern. The caps have a concave inside so it rests pretty well without getting off balance. After about 30 minutes, the seal chipped right out.
Motorcycle Dan suggested posting this tip up so here it is. Hope you have the same success I did.
Not just another pretty face.