I did not meant that I have seen anything horrible inside - in case it came across like that. What I meant was that it is filigree (if this is the right word) work and pulling on it might bend and warp something.
Indeed, while fixing the loose knob on mine I noticed that the center screw is slightly warped and this might be related to the impression of “irregular spots” @tambouri reported.
I although wondered if it could be caused by some mechanical warping happening while shipping (i.e. flying) due to extreme temperature changes.
Although I am perfectly convinced that it still works without issues that make it impossible to use for shows/touring.
And I can see that designing a mechanical objects is quite a task. I am thankful that you did this as it is a promising instrument and I am sure it will be great when the software is fully developed perhaps some more of Arcs potentialities have taken full effect in it.