Repair and cleaning C8 with loose secondary mirror

Problem:
We received a C8 (Celestron 8") with a loose secondary mirror. Unfortunately, this is not an uncommon problem with this type of telescope.
Over the years and with regular use of the screw mechanism on the secondary mirror, the glued foam rubber loses its tension and hardens with aging. This causes the secondary mirror, along with the retaining ring, to rotate loosely on the Schmidt plate.
Since, unlike older models, the secondary mirrors are now symmetrically ground, the rotation of the secondary mirror no longer significantly affects the image.
However, with continued use, the mirror rotates further and further out and can tilt and eventually fall out of the Schmidt plate.
In addition, the Schmidt plate on this telescope was heavily soiled.

Solution:
Sometimes you can solve the problem yourself by removing the retaining ring and then carefully removing the secondary mirror. You can then carefully grasp the inner ring and tighten the mount again by turning the outer attachment.
Caution: Do not touch or even touch the Schmidt plate. Gloves are invaluable here.

If the moss rubber has hardened too much, this will unfortunately no longer help, as pressure must then be applied to tighten it. And pressure must not be exerted on the Schmidt plate under any circumstances.
Then the only solution is to remove it.
This was also necessary with this C8, and the Schmidt plate was carefully removed.
Tip:
Pay attention to the position of the Schmidt plate. Unlike the secondary mirror, the plate must be perfectly aligned with the primary mirror. This can be identified by markings on the edge of the plate; in this C8, there were two notches.

Since, as mentioned, the Schmidt plate was very dirty, the outer side of the plate could be cleaned immediately after removing the plate and the secondary mirror. Extreme caution is required here, and any pressure or excessive friction should be avoided. First, remove dust and microparticles from the plate with a blower!

With the secondary mirror removed, you can now screw the secondary mirror mount into place with light pressure.

With a lot of patience and a few attempts, you can then return the secondary mirror and Schmidt plate markings to their original alignment.

Tip:
The original settings are: secondary mirror notch = 3 o'clock; plate marking = 5 o'clock, or 6 o'clock on some models.

A word about cleaning Schmidt plates:

A Schmidt plate rarely needs cleaning. Dust particles or small streaks do not affect the optics!

The glass surface of the plate is coated! This coating reacts sensitively to mechanical and chemical stress.

We only clean Schmidt plates in absolute exceptional cases!

If you absolutely want to clean the record, please note 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 lint-free microfiber cloth.

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 to ensure they are returned to their original position.

If this is too much work for you, please feel free to contact us for inspection or repair (for a small fee).