These are all links from Brad's Home On The Web where he has random personal photo sets, but also lots of great shots of restoration projects he has done. He describes himself as non-professional, which means a lot of his work is a lot more approachable for the rest of us that are learning.
I've linked to a handful of his great examples, and each seems to have 100+ pics of the process.
The restoration of a 1979 Williams Flash Pinball machine
Paragon Playfield Restoration
My 1978 Bally Lost World Pinball Machine
Firepower pinball playfield swap
1977 Bally Black Jack Pinball Repair
And then if you want to get a bit more INTENSE, there's always Ed Cheung...
Space Shuttle restore (4 parts)
Bride of Pinbot
and all of his other pin projects