Hugh is spot on with his comment. I am working on restoring a Bally Eight Ball. Mr. Pinball says one in good condition is worth $775. I bought a CPR reproduction playfield ($500) to drop in it and am adding some new parts here and there. I've already lost money in this machine according to how much I paid for it and what I've put in it so far. However, I have thoroughly enjoyed every minute of this restoration. I have learned a "ton" and can finally see the light at the end of the tunnel. I can look back and take great pride knowing that I did it. I plan to practice touch-ups on the old playfield to learn that skill.
As for tips, you've gotten some good ones already; taking pictures; sliding your assemblies onto foam board while swapping, etc. One thing I've done is when I remove an assembly, I put it and all the screws, small parts, etc. in a zip-loc bag and write down what it is and where it came from. That way I'm not searching for that one piece I need when putting it all back together.
If you decide to tackle it anyway, enjoy yourself. It is quite rewarding.
Phil
