You sure there are manufacturing errors in this? 1937 would have had rigorous inspection, plus 2 years of use in field maneuvers before
the war started.
The meter replacement plate indicates it was repaired somewhere along the line and the def meter dispensed with.
I think the production changes as the war went on are very interesting. The internal shielding decreased in size and then was mostly
dispensed with. I saw that two different productions had regen control shafts of different diameters, so a knob for one would not fit
the other. Odd.
-Hue Miller