Brian, if nothing works, go to a bicycle shop and ask for an old inner rubber of tire. Take old original gasket and copy with ball point pen all marks to cut with very sharp carpet knife or scalpel careful the new gasket. You have enough rubber of tire for practice.
We put the rubber under trims around car and on many other edges where it helps to avoid sharp contacts on body like bumper etc. Very usable stuff...
hannelore
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