I had a bizarre issue with the left flipper on my JP. Rarely the left flipper would not work at all for a minute or maybe less and then it would work fine for several games and repeat. Now, when the problem occured I quickly opened the coin door and slightly pushed the EOS switch near the contacts and it would come back to life. Of course you'd think the EOS switch was 23 years old and beat but the seller actually had his tech replace it (looked brand new and super shiny). I did rebuild all the flippers but left this EOS alone since it looked new. I then replaced it anyways but still no dice. I had it adjusted so that that when the flipper flipped the NC EOS leaf actually moved forward a tiny amount indicating there was some proper swipe/tension. The motion was identical to the right flipper. Still nothing. I found a splice shortly down the line in one of the EOS wires and removed it (there was enough slack) but even then no dice. I checked out the flipper board and reflowed the fuse holders and connectors to no avail. Despite all this I didn't give up and found a bulletin issued by Data East (No. 54) that pretty much tackles this exact issue, sort of. The main issue was the leaf switches would crack at the bakelite but seeing as I still had the issue with two brand new switches that wasn't the problem. I ended up doing the #3 solution which was modify the board with some resistors, diodes, and capacitors. Ever since then the problem is technically "fixed" but I feel this was more of a workaround than an actual fix as I haven't found the original cause of the issue.