I feel fortunate, in that I traded 8 hours of software authoring for a 1971 Bally Sea Ray machine. The client was using it as a paper goods storage surface. I

I feel fortunate, in that I traded 8 hours of software authoring for a 1971 Bally Sea Ray machine. The client was using it as a paper goods storage surface. I brought it home, repaired the power cord, and played. It was so-so. I then started researching, found a trove of data on restoring/repairing, learned to be careful of the back panel art as well as the right kind of wax for the playing surface, and much more. I also found companies offering replacement rubber kits, as well as spare bulbs, springs, etc. Armed with that and a repair manual, I went through the machine, taking all of the play field apart (after photos), waxed the play field surface, carefully cleaned the parts, put them all back together, replacing burnt bulbs, broken springs, and so on. There was also a lot of cleaning of copper contact points, as well as removal of oxide from the solenoid shafts and housings (some 20 or 30 of them). New rubber _completely_ changed the dynamics - What a blast! The ball was suddenly flying around, sometimes even hitting the glass top. It is all solenoids and relays, with one main motor that controls timing. When the ball contacts a target, it has a conducting back surface that comes into contact with another vertical contact situated right behind each target - This completed circuit energizes a specific relay, "saving" the state that the target was hit for the next subsequent rotation of the controlling motor. Without this "save" the target hitting occurs far too rapidly to be caught by the electro-mechanical machine to be scored. The motor steps/rotates one step with each registered score (or multiple scores, again due to timing), with the appropriate "score" going to either a 10 point mechanical wheel or a 100 point wheel and each energized relay de-energized (re-armed, as it were). The motor shaft also has several (6?) discs with raised tabs at strategic places on the edge that are "read" by micro-switch followers to control various parts of the scoring electronics. The score wheel rims are labeled with the score digits, rotating like an older odometer (or gasoline pump display) with the current status (points, games remaining). All the smaller targets hit also serve to rotate an axle that has some 20 or so copper wipers that may or may not come into contact with a random assortment of contacts laid out on a circuit board - This completes the circuit and lights up the next "randomly" lit target(s) (imagine your hand with fingers out-stretched rotating around the center of your palm with the tips of the fingers touching on a surface that may have contact points and you get the idea). I also re-enabled the tilt-mechanism - A plumb-bob-type affair suspended within a conducting frame - Move the machine too much and another circuit is completed from the plumb-bob touching the frame, through to the tilt-circuit. After all of that work, rather than fit an opaque back to the back box (the original was missing), I used a sheet of Plexiglas - You can see electricity arcing during operation with the room lights turned down. Lots of fun, time to clean it again.