Can be either the OTA itself or a complete but sad telescope. Celestron only.
Regarding the OTA.
The following damage is OK:
- Corrector plate and or secondary hopelessly dirty or even broken or missing
- Tube badly dented, gouged, and or scratched (the tube only)
- Primary mirror coating hopelessly dirty, but NOT pitted!
- Any combination of the above
BUT, that is all.
The primary mirror itself, its mounting baffle, slide, focusing mechanism, and the back casting MUST be in fairly good shape: the primary MUST focus smoothly!
Regarding the mount, if any:
It can be any type from an old spur gear to a newer worm gear dual fork or even a NexStar 8 single fork.
If the mount is dirty or scratched that is OK and adds a small amount of value. Mounts with significant mechanical damage or are sprung are not worth much.
So, if your old C8 or C9.25 is growing things inside or has been dropped, let's communicate.