Gorilla, I'm in the same boat as you. I still get timid because all my games generally work well, so I toil over do I want to dive into one just because the right side GI lighting isn't working and I can see where the J-connector has melted...but in time.
I'm not up to that level just yet, but I have fixed several bad switches, replaced some old rubber, and put LEDs in my T2. I hound the tech that works on our games in league play, look at the manuals from ipdb.org and the pinrepair documents, and I print all this stuff if I can.
Next challenge is the right flippers on my FG just stopped working, so finally a game I can't play unless I fix it. I think we're in good hands here, and give us some time and we'll become more confident.
I think testing my soldering skills on a board I don't care about will be the next step after fixing these flippers. We'll get there.