On Feb 27, 9:51 am, Ignoramus27827 ignoramus27...@NOSPAM.
27827.invalid wrote:
My obvious question is how are these gauges usually adjusted.


All of the gauges I've adjusted (deliberately G) have followed the
same pattern.

1) you cannot "calibrate" most bourdon-tube gauges, except at a single
pressure -- that may be why it's 25psi off, or maybe not. The spring
quality of the tube is usually the only spring element, and its
tension is not readily adjustable. IF it has a separate balancing
spring, there may be room for doing some range adjustments.

2) you rotate the hand on the shaft to calibrate it. Sometimes that
involves loosening a hold-down screw that penetrates the hand;
sometimes the hand is held on by friction.

It almost always involves holding the pinion behind the face with some
sort of grasping tool so as not to over-stress the rack assembly.

LLoyd