Vixen VC200L Mirror Cell Adjustment

I have been experiencing the famous "triangular" stars that so many folks have noticed with the VC200L. I decided to open it up and see if I could find any sources of pinching. This page describes the disassembly and insides of the VC200L. For more on my triangular star investigations go here.
After removing the black phillips screws around the base of the tube it was easy to seperate the tube from the rear housing.
At first glance it seems like the retaining ring with it's three sets of double screws might be a good source of pinching. Upon further inspection, however, I found that the screws were quite loose.
With the retaining ring fully removed you can see that the ring is supported by three blocks that have the proper gap to allow for mirror movement already machined into them. These block are made of some sort of dense rubber and could be overcompressed but were not in my case.
After removing the ring I could look down into casing and see the mirror cell and some sort of cork shims. I decided to go further.
Removing the three "pull" screws for the focuser collimation frees the focuser and baffle tube assembly for removal.
With the rear casing and mirror cell seperated maybe we can see what's going on.
Now we're getting somewhere. We see that the aluminum mirror cell holds the mirror in place around the edge by the use of six brass and cork shims. These shims are tensioned by six set screws.
According to the Vixen FAQ the mirror is supposed to be able to move from 0.5 to 1.0 mm in the mirror cell. When I checked my mirror it would not move at all. I loosened each of the six set screws just a tiny amount and then I was able to move the mirror side to side by the prescribed amount.
I reinstalled the six screws that hold in the retaining ring on top using Loctite since these screws have to be left fairly loose so as not to compress the rubber stops.

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