Interesting. I would guess that the pinion that rides on the rack is spring loaded to maintain intimate contact.
I have an import caliper that I dropped once. Ever since then, the zero has been off by about 5 or 6 thousanths from the top. I have checked it against my mike and other calipers and am confident it is accurate (+/-0.001") but it is puzzling. It seems to me that if it skipped a tooth, it would be off in a multiple of 0.025". So I wonder what happened here. No obvious way to disassemble or I would have done so.
Make it fit.
You can't win and there is a penalty for trying!