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Ít sounds like the bushes in the "S" linkage are getting worn possibly along with the screw. A good tech should be able to replace the worn parts for you. I have known people to use a drop of STP in such situations but it will most likely slow things down. Anything viscous enough to absorb the energy required to make noise is likely to be sluggish as well.

See if there really is play at the connection while holding the rotor arm so it doen't move. It is also possible that there is some end play in the valve itself which is activated by the fact that the linkage would like to move up and down in the space it occupies in the rotor arm.

Depending on the extent of wear you might find it advantageous to convert to modern ball and socket linkages. A few of the techs here could probably give you a good estimate of cost for such a conversion.

In which scenario do you hear noise?

(1) Take a precision screwdriver and make sure all the screws are tight. I'd use a small precision screwdriver because that makes it more difficult to torque off the head of one of the screws by accident.

(2) Grab the stop arm and hold it against the bumper so the valve cannot be depressed. Then try to press the valve lever. If you hear some clicking, then there is play in the linkage. A good repairman may be able to swedge the worn parts in the linkage and quiet it down.

(3) See if you can wiggle the stop arms side to side. If you can and that produces noise, try oiling the bearings with 3in1 oil or sewing machine oil. If that doesn't work around the problem to your satisfaction, the bearings probably need to be swedged. You need a really good repairman.

(4) If you grab the stop arm, and pull it up and down, is there motion? Does it move? If so, remove the cap off the bottom of the rotor and make sure the back plate is all the way in. If it is, a repairman may be able to remove the back plate and take a tiny bit of material off of it so it seats in just further enough to eliminate the amount of play.

If you need any help with any of this, send me a PM. I'd be happy to help you out.

tuben wrote:I know where the noise is coming from, but don't know what the exact term is.
The noise is where the S-linkage connects to the rotor 'spindle'.

So... you must be speaking of where the 'S' arm attaches to the stop arm (the 'thingie' that has the pin on the bottom of it that strikes the bumpers).

Assuming that there is enough clearance between the screw and the stop arm for you to actually see movement....

In some remote cases, the screw has been replaced with one that's soft and worn. In this case... locate the correct hardened screw... which is usually tapered. If the screw is OK and the 'S' arm has an elongated hole... the hole can be peened and refit so the clearance on the screw is minimized.

FWIW, this is a horn you worked on, Dan, maybe 4 years ago.

jeopardymaster wrote:FWIW, this is a horn you worked on, Dan, maybe 4 years ago.

Either I did a good job and it was played hard for four years.... or....

Oh geez! Never my intent to embarrass you, Dan - just to refresh your recollection. You did great work on the horn, particularly to reseat the bell, de-dent that ugly spot on the upper left hand side, and patch the fourth valve pipe - which I hadn't known was a problem. Played so great when you were done that I was super-reluctant to sell it. Valve clatter was not a problem then - it could have something to do with Mr. Coulter's fingers!