I was lucky enough to purchase a Star Trek the Next Generation Pinball about a month ago for about 3k. The machine was really really dirty, it was supposedly HOU, but the people that owned it had no idea how to properly maintain a pin. When I opened the back box to look at the boards (battery damage in particular) he was surprised there where boards back there 
As soon as I handed them the cash I ripped those old batteries out lol.
I will say that I have much more appreciation for the professional restore/High End restore folks. This was a lot more work than I thought it would be... well I knew was going to be a ton of work but still..I'm an amature, I've never done this before stripping a pin down this far top to bottom. It's such tedious work, I had no idea, this pin in particular has so many friggen parts and I thought the top of the playfield was bad but under it was much worse lol.
Anyway, I've finished it as best as a amature with a full time job can do, I learned a ton and overall it was a great experience. Here are a few things I did...
Removed everything from the playfield
Polished all the metal pieces and bolts (had to do it by hand)
Replaced all plastic with new (old plastic was yellow, some missing and some broken)
Polished the playfield - This was a bit scarey...I was just afriad I would damage it but I had to get a little agressive to get all the grime off it.
Removed all mylar (freeze method is awesome! Never done that before Youtube ftw)
Cabniet was in really good shape besides a few knicks here and there that was I able to touch up.
Rebuilt flippers, pop's, Vuks, removed and cleaned subway (uggggg) and all those prox sensors
Had to replace the trough boards they where intermittent and original
Added some mods I wanted along the way
Overall it turned out pretty good, I learned a ton and have a much better appreciation for the hobby. Here are some pictures before I started... I'll post a video and pictures after for those intrested.
Middletown, OH
