I have recently learned that cleaning an SCT is no big deal. The procedure is roughly as follows:
1) Remove corrector
2) Remove Focuser Assembly
3) Remove Corrector Retaining Ring (basically the lens cell for the corrector)
4) Reach into scope and remove split ring on the spindle that stops the mirror from falling off the spindle
5) Carefully reach in and pull out the mirror
6) clean the scope and put everything back together - installation is reverse of disassembly. Take the time to regrease the focuser.
Two rules I follow. 1) Don't touch or disassemble the secondary. I understand they are set at the factory. 2) Very hard to remove the mirror from the spindle because they are RTV'd to it. Also if you do so re-aligning so that the mirror square to the spindle can be a pain. You can wash the mirror in its spindle with no problem.
Here is some references to these procedures:
(This one is good).
Just take it slow and be careful. You will need to shim the corrector in the same way it was when you took it apart (paper shims).
Edited by Brent Campbell, 23 June 2022 - 04:31 PM.