I just bought myself a pre-owned non-sensitive, 2.25" UMA altimeter. All looks to be in order, however the subscale is out and it under reads by about 900ft. So I need to calibrate it. Anybody knows how I do that...? It doesn't have the adjustment screw that the bigger ones generally have. Here's a picture:
https://photos.app.goo.gl/8Q81MQSP8sAtXdjK9
https://photos.app.goo.gl/8Q81MQSP8sAtXdjK9