Sorry pooch, I wanted to add to post, double-posted, deleted the first and then found your response. Few yrs. back, there were several threads on this subject which discussed Oscar Gaddy's [now discredited?] piano wire tension spring. They may still be archived or perhaps the langoliers have done their work. A number of us followed Gaddy's lead by modifying commercial guages or scratchbuilding our own to include the spring. Look at the photo of JDW's "table" gauge. The brass rod pivoting in a slot cut in the interior rod and no question hiding a coil spring behind is the same principle for the same purpose with a different execution. I'll see if I can find a picture and will post if I can.

jack