With the advent of google, maintaining pretty much any marker should be pretty simple. And for the not-so-simple, there are people here to ask.
It really all comes down to air flow. Once you can wrap your head around air flow and a few moving pieces, it helps significantly to be able to troubleshoot anything.
I have cockers and mags. I also have a blazer and a phoon. I love fully pneumatic guns...but my mag easily outshoots them all (it's a pneumag) and is probably my current favorite. Although I have recently decided to build a new e-cocker...
My recommendation is this: get whatever you want to tinker with and plan on it being broken for a good amount of time while you learn the ins and outs. Once you get it sorted out it'll be a real sense of accomplishment, and you'll be surprised at how much the tech side of it starts really just naturally coming together for you.