Ice-Racer : the 138-series were made over quite a timespan, and there were variations to them.
I have a couple of them, and even the detent has a correction feature, allowing it to be fine-tuned.
Now foward/backward tilt on the lens mount is a different thing. It's highly rigid to begin with, but
could be hypothetically skewed with a very heavy lens. The only really massive lens I use is on my
customized 8x10 color enlarger, which is built like a tank and has micrometer corrections for everything. That was a challenge; but I really lucked out and found a solid machined bronze tilt &
yaw correction device originally intended for WWII mortar sights. Something like that would cost a fortune to machine new, but I got it for free was able to quickly adapt it to my enlarger column.