A friend of mine recently took delivery of a phenomenal Jeffries 30-button which had some serious restoration work done by Dipper.
The spring tension on all the buttons across the board is quite high, which she's adapting to, but the air button has about twice the spring tension of the other buttons on the instrument and I think is way too high. The air button actually painful to use for any length of time and she's getting tendonitis in her thumb from activating it.
Looking at the design of the air button, it appears to have a single-wire, double sprung mechanism unlike the other buttons on the instrument. It appears to be a single-piece V-shaped saddle spring with two coil springs on either side of the lever.
This is way beyond my ability to adjust, any suggestions who might be able to do the work for her to lighten the air button spring tension without having to ship the instrument all the way back to England? She's in San Diego, CA.
Thanks for any suggestions,