Man that fuel cap gasket is such a bummer, mine did the same thing after sitting in my parents shed for a decade. Good news is you can still get rebuild kits for those old tanks, the gasket and pump cup are usually like ten bucks online and take five minutes to swap. I did mine last fall and it's been running like new since. Those old Colemans are worth fixing, they outlast anything you buy now lol.

Read a thread on Reddit about this exact thing. Some guy had the Red Wedding ruined for him by a buddy who thought he was joking. He said the worst part was the guy did it like it was nothing, just tossed it out there. Another person said they just stopped watching the show for a year. Weird how one sentence from someone else can wreck weeks of buildup. I had a friend spoil a game ending for me and I sat on a spoiler for his favorite show for months. Never used it. Just knowing I could was enough.