Enjoying this thread Mitch .... watching with interest while I try to locate a reasonable project Flash to try a first restore on.
Good luck, there was a few Flash machines around a while ago (my dad has another 2!) I have found them as a good first restore as long as you know or are good yourself at board-work, The main boards in the Backbox are conected with a really dodgy connector, it becomes dirty and gets bad contact after ~10 years. another thing you want to look out for is playfield wear... thats where the paint has come off from the ball rolling around after years of being played in a pizza bar; ect. unless you are good with an airbrush then try getting one with no or little playfield wear... ps. you can buy genuine stickers for certain areas of that machine.
I hope you learn as much as I will from my mistakes and find what your looking for,
Good Luck finding a machine!