Omega Seamaster Cosmic 2000 Restorations

Regarding the sapphire caseback. They are not available, the movement case is a can with a base and a lid (the crystal) and the insides are accessed when the crystal is removed.

You wouldn't want a transparent caseback anyway, the caliber 1012 is a particularly unattractive movement and is better left hidden.

Removal of the movement is usually accomplished by pumping compressed air into the stem tube after the crown is removed.
However, this may be problematic in your case as the cracks in the crystal may prevent internal pressure popping the crystal off so the correct press/dies will be required to press it apart.

It's a job for a skilled watchmaker with the knowledge, appropriate tools and access to parts. Preferably one with an Omega Account.

Edited to describe the case style.

Here's a video that shows you what's involved.

Repair would involve a service by a competent watchmaker. You don’t say where you are (UK, Aus, US?), but there are plenty of threads for recommended watchmakers on the forum if you do a quick search.
This is a strange/unique case type, using a variety of gaskets and friction fit parts. Sapphire case backs I expect aren’t available.

Snap!



It looks similar, if not identical, to mine which has ref 166.128 cal 1012 from 1974.

As stated above, knowledge and skills are required to open the case without damage, but it is possible to find watchmakers to service and, I presume to change the crystal. The company that I used are Omega certified and have a parts account. However, even they were unable to get an original crystal, but replaced with a generic one, which is fine as it is flat glass.

I hope that you enjoy your Cosmic 2000, it is a sporty kind of watch. I wear mine a lot. As it happens, mine was also gifted to me from my father, who was apparently wearing it at my birth(!) all those years ago...