For anyone attempting this endeavor, here is an excellent guide, not all scopes are the same, for example I didn't have to remove the corrector plate ring on mine to remove the mirror.
[cloudynights.com]

Done and done. The scope came apart so easily I couldn't stop to take pics, before I knew it the scope was in pieces. I didn't expect that to happen, I kept waiting for all these small pieces to fall out, no small pieces inside.
I did solve the massive image shift problem. Note to self: use shorter screws next time so the mirror doesn't hit them causing massive image shift.
There was no old hardened grease on the threads of the focuser, the grease there was soft and not overly applied.
Question: Anyone seen a focuser assembly with two sealed bearings like in the pic? One I can understand but two of them stacked?
Scope is a Celestron Super C-8 Plus, circa ~1986.

Love old scopes!

Wow, good luck! I am interested to hear how it goes. If you take pictures as you work, those would be interesting too!