The Home Machinist!

I've had a Starrett 6" (#150?) from a trade about 20 years ago that has always had the needle at 9 o'clock when it was at zero. After the discussion of a few days ago, I decided to try to correct it.
Had success after I cut a piece of .005 brass shim stock, about .050 wide and 2" long. I put it on top of the rack on the RIGHT side of the "carriage" and forced the carriage to the right which took the pinion gear out of mesh with the rack. I got lucky, first attempt brought me right to zero.
Years ago, I was responsible for about 30-40 6" Helios dial calipers used by floor inspectors at a manufacturing plant. Mostly women, I could count on at least one "out of zero" caliper every couple of days. I had a very thin copper shim that I used on the Helios but it would enter from the LEFT, the Starrett would not.
I cut the bristles very short on an acid brush and that was my tool to clean out the crap that would get in the rack and cause the pinion to jump. Still have that little brush and use it on the few dial calipers that I still have.