A few years ago, I replaced the cork seal with a new rubber seal, and the cap is very hard to get on and off. I keep saying to myself, "I need to put a little grease on the gasket" but somehow I never do...but I suspect it will make it much easier to deal with.
The rubber gasket was an aftermarket one from WorldPac.
Deers Dears,
Throw that ole cork seal away (or store it in your display cabinet, or use it for AACA or MBCA show purposes only),
go & get a new rubber seal, part no. A140 471 00 79 for the cost of about $$ 2.50
and put a little MoS
2 grease on the top of the fuel filler neck and the visible side of the seal
& enjoy!
However, with the time gas (petrol) "dilutes" grease (i.e. "washes" it off); therefore, re-lube the seal once per year again.
You'll never ever have problems again.
IMHO...
Achim