Then the multi-strand wire was traded out for a single piano wire on each side. After that there was no way that I could get the servo to dance. I tried more and less tensions. No change!

The weight difference was .09 oz

I put the O-ring back on to stop any pull-pull wire “humming” and that how it has been left.

[In case you think I have lost it, don’t forget that we can’t fly yet and the building is all done!]

Flight trials will tell the rest of the story.

Regards,

Eric.

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If I understand it you still have the solid piano wire on it and the o-ring. You not only got rid of the low frequency oscillation but the high frequency buzz.
The solid wires sounds easier and cheaper than the carbon rods.
Does the servo buzz with no load? The o-ring probably adds some friction which is okay as long as the servo centers okay.
Good work. Now we know there is a solution.
Jim O