Posted by js on April 03, 2003 at 00:14:41:
In Reply to: Yamaha valves posted by Chad on April 02, 2003 at 18:05:26:
Remove (or have removed) the brass oxide deposits from the piston surfaces, and do so on a regular basis.
Yamaha piston valves are very frustrating if they are not babied (surface-cleaned very regularly). This dates back to as far as anyone can remember with the history of Yamaha "stainless" piston instruments.
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I didn't read any of the other posts, but I'm willing to bet $1 that others told you the synthetic oil was mixing with the Blue Juice and causing a problem. As certain as I am (without looking) that others suggested this, I'm certain that the mixing of oils is not your primary problem.