Hi JA,
Yep, you are right, actually I did two of my Cats (also tried the third one (Rubinar500/8), but no improvement after process), with success (MTO 1000A and MC Rubinar 10/1000).
The thread is
here.
In the first post there is a
link which inspired the whole process.
Steve,
Your image definitely looks like a bad case of "pinched optics" (almost always main mirror is affected).
I found that the mounting of lens body (well.. this is a scope now) has effect too.
Too tight bracket around the back side of my MTO resulted in images
like on this link .
All in all, the main mirror should NOT be tightened at all.. just lightly touched by retaining mechanism, just enough not to rattle inside.
I also added 3 kapton tape seats (procedure described in one of links on Dr Strickland's webpage).