Someday I'll own a Playtime just for nostagiac reasons. As kids, we figured out if you could get the three numbered featured at "111" (which scored a replay when the ball drained) -tilt the machine! Get the replay, tilt again, another replay, etc. until you maxed out on replays. When a new game started, the player's score reels rest, but this score feature stayed right where it was (111).
I remember the Op coming in and comparing the play meter to coin and getting pretty ticked. When he was trading this machine out for another, I told him what we were doing. He tried it, shook his head, and thanked me.
This was at the Teen Center on the Air Force Base my dad was stationed at. He asked how we were cheating the GTL Surf Side and CC Gun Smoke at the Airmen's Cafeteria. I told him I didn't know of the Cafeteria, and if they had pinball machines. I was lying. What never made sense to me- Surf Side and Gun Smoke stayed at the Cafeteria for years, even though the Op knew someone/most were cheating - just by the plays vs. coin - yet they didn't replace them. They had 4 machines, but kept replacing the ones we couldn't cheat to win for the 6-7 years I was there.
On the plus side, watching the guys repair the machines here was when I got the bug to own machines. I would tell the techs what was wrong, watch them fix the machines, and learn. Sometimes, this little kid would tell a tech how to repair a machine.