Where to start. Firstly, 'cockers need loads of maintenance = myth. My Ego10 needs more maintenance than any of my 'cockers.
www.customcockers.com/forum is a must. Become a member and read everything.
Assuming the marker works - don't mess with it. Put a few drops of oil in the ASA occasionally and you should be good.
The best way to learn about them is to understand how they work. Use it, examine it, watch how the parts cycle. 'Cockers have a mechanical quality (even e-cockers). When you understand the way the parts interact, problems become a lot easiier to diagnose.
^^^The TechPB video is excellent for a begginer.^^^
What model do you have BTW?