I have a rather expensive air gauge I bought a few years ago from Joe's Racing. A few months ago I dropped it on the concrete floor of my garage and knocked it off calibration. It has been laying around ever since waiting for me to throw it out. So today I was cleaning off my garage workbench (separate from workshop in the basement with its own set of tools) where I do my mechanic and outdoor work from. I decided to take it apart and see what makes it tick inside. These are the components once I had it broken down. Whenever something breaks on me I will often take it apart in order to reverse engineer it. Generally, I don't have aspirations for repairing it. But at least I'll poke around and see what it is all about. This time I got lucky. This is what the mechanism looked like on the inside. I activated it without the housing around it by pressing it on a tire valve stem to get a pressure reading. I realized watching it, that the copper curved armature expanded under pressure causing it to rotate clockwise. It moved the needle on the presentation side offering a pressure reading. So in order to recalibrate I merely had to bend the copper armature to zero it out, thus regaining the original calibration. What I didn't know is just how delicate the movement actually is. The first time I bent it the arm barely moved and yet the needle jumped all the way around to 50 psi. Oops. It was like trying to push a snowflake across a table top. After a great deal of trial and error I seem to have found a zero point that matches one of my other gauges and have restored the calibration. I'm glad to have it back on the wall in working order. Sometimes you get lucky and restore a tool to working order. At the very least you will probably gain some knowledge of how something works. Thanks for looking and hope you learned something too.