Back in the mid 80's I was a CBM authorized svc tech. for a CBM ASC.
I quickly learned to use only machine pin sockets, as they were mechanically & electrically better than the cheaper ones. (I hated callbacks).
If you really need a schematic, Howard W. Sams covered the 2 (USA) models of the CBM computers, and there is a slight possibility I may have OEM svc literature for the U.S. models still...maybe... That was 40+ years back.
Mostly they wanted us a board changers.
The highest failure item I ran across was the floppy drives failing.