Another question about the 12 year (or so) old Buffet B12 Bb clarinet I inherited recently. Apologies in advance if it's been asked a thousand times before. Either one or both of the ring keys for the F (thumb) and or F# are sometimes, but not always, slow to rise when depressed and released. I say "one or both", because I'm having trouble isolating the actual problem. It sometimes seems as if the ring on the thumb key is catching on the nickel silver post, and then it seems like the F# key is sticking on it's post, when played alone. I also wonder if the pad that goes down when both keys are played is sticking, but that's my least favourite choice of culprit. Would there be any mileage in cleaning inside either of the rings? Or is there a more likely problem - and solution. Thanks for any comments and all the help so far.