I'd just buy a rubber one at the hardware store if the trip to the LHBS is out of the way. It won't hurt for a few days so you can tune in the kegerator and try it out. They may even have a silicone or neoprene washer there. I never looked.
What year is this?
It's the Viking age.
That explains the Laser Raptors! F***! I went back in time too far! - Kung Fury