Next time it sticks, turn off the game. If it stays up you have mechanical binding. If it drops immediately after turning the game off you have an electrical issue.

From what you describe, it sounds mechanical.

Try playing a game again and when it sticks, turn the game off and report whether or not it dropped when the game turned off.

I would start by cleaning the flipper opto boards, if that doesn't help swap the left and right boards and see if the issue goes away.

Check soldering and diodes on the coil.

LTG : )

TAF is fliptronics but doesn't have flipper opto boards.

Check gap and clean EOS switch on the flipper as well as flipper button switch. Compare to the side that's working. A binding EOS switch or cabinet switch, even though a mechanical issue, will act like an electrical issue once power is removed.

I had the same problem about 3 months ago. Did exactly what you did and it fixed it

I have this problem now as of last night. Turn on game.... Right upper flipper works right for a couple flips. Then stays up until the left flippers are hit for a few times. Then locks and stays unless I turn off the machine. Diodes all test good. Eos operates correctly. Looks just like the left one. Reflowed solder on all coils. Same issue. Going to replace q15 and q7 and see how that works.

Did you lift one leg to test ?

LTG : )

Diode on the faulty coil tested bad. Replaced it and issue remains. Transistors being replaced tomorrow

Replaced the tip102 flipper transistor and all is better. The old transistor tested as working but apparently failed under a load. Thanks for the help.