Hi Joseph, with apologies to my friend Richard for the moderate derailment of his thread, I noticed that you are now playing a Shires Q41... Thus, I...
I would suggest pouring about a quart (or however much you can get in) of Simple Green Solution down your lead pipe while while working your valves....
What was the date of the recording? I am wondering if this was an outdoor concert or possibly when The International Music Camp was doing performing...