Whoosh...
just like pulling a cork out of a bottle, I seem to have a slight vacuum when I pull mine off too but not to the degree of dificulty that your wife describes. Maybe a combonition of the slight vacuum and the gasket being dirty/sticky is what she experienced. Practice practice practice, maybe you should build some sort of exersize system to build her hand strength?
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy