Posted by Paul R. Ogushwitz on December 21, 1998 at 13:00:35:
In Reply to: St Petr. Rotary Valves posted by Ugo Boscain on December 21, 1998 at 12:10:38:
Suggest you start by oiling the moving parts. Turn the instrument upside-down, remove each bottom valve cap and place one drop of oil on each bottom journal (bushing). Replace bottom valve caps. Turn the instrument valves up and place one drop of oil on each valve shaft so that the oil runs down into the top journal. Then oil the pins at each end of the pushrod, and oil the finger paddle assembly where the paddles rotate around the axle.
Then work all valves repeatedly until the noise goes away.
If the noise does not diminish, then there are other problems with the mechanism.
A precision oiler or medical syringe is an excellent tool for precisely placing the oil drops.
It sounds as though you think there is excessive clearance between the rotors and their casings. I recommend you have an experienced repair person check that for you. If necessary, the rotors can be built up somewhat with copper plate, refinished with a hard metal (such as nickle), and lapped for a tighter fit.