Repair and cleaning of a C9.25 Schmidt plate

Problem:
A customer sent us a Celestron C9 SC telescope (of a newer model) whose Schmidt plate was smeared inside and out(!) and whose secondary mirror was loose (could be rotated freely from the outside).
Since the Schmidt plate is coated (anti-reflective), mechanical cleaning of the Schmidt plate or even using commercially available cleaning agents should generally be avoided.

Solution & Procedure:
In the first step, the retaining ring for the Schmidt plate is carefully loosened. It is important to pay close attention to the exact location of the mark on the Schmidt plate (usually at 3 o'clock on this model).
In the second step, the three retaining clamps (this is new for C9s of a newer model) are loosened. These are small rubber plugs that are released by a screw on the outer ring. The exact position and distance should be carefully noted.
In the third step, the secondary mirror is attached to the removed Schmidt plate. Here, too, it's important to ensure the marking is in the correct position (it's usually at 5 o'clock on this type of mount). On the newer C9 model, the two (inner and outer) mirror mounts are screwed together, not glued as was the case previously. Keep a close eye on the marking when screwing them together. The tightening pressure should also be just high enough to ensure the mount is secure, but no tension is created on the Schmidt plate.
In the fourth pass, the Schmidt plate is cleaned of coarse particles using a small blower.
In the fifth pass, the Schmidt plate is cleaned of streaks and smears using "optical cleaning spray" and a microfiber cloth.
In the sixth pass, the Schmidt plate is reattached to the clamps in the correct marking position and secured with the retaining rings.
In the seventh and final pass, the telescope is adjusted and tested against the artificial star.

A word about cleaning the Schmidt plate:
A Schmidt plate rarely needs to be cleaned. Dust particles or small streaks do not affect the optics!
The glass surface of the record is coated! This coating reacts sensitively to mechanical and chemical stress.
We only clean Schmidt records in exceptional cases!
If you absolutely must clean the record, please observe the following points to avoid causing permanent damage:

Do not allow (skin) oils or acids to come into contact with the record - wear gloves,

Human skin is a carrier of oils and acids!!

Never use household cleaning products - no glass cleaners, dish soap, or similar.

Use Optical Wonder and a microfiber cloth (lint-free).

Do not apply pressure to the record.

Never wipe particles away, always blow them away.

Do not blow with your mouth, only with a blower.

Pay attention to markings and retaining plates, ensuring they are returned to their original position.