[TPIN] Bach valve repair

[Achias1 at mchsi.com]

My 1972 Bach is starting to lose the thin cork circles which keep the valve from
clicking when it returns.

My local repairman gave me a tube of cork with a hole in it and told me to cut
off whatever I need, but that doesn't seem very accurate to me.

Are these corks available to order somewhere, or do I need to take it to a more
accomplished repair dude?

Dave