Desoldered coil to check resistance. Was a little low. Jumped to other flipper and it worked fine. Incoming voltage on blue wire is fine. Incoming ground on blue-violet showed no connection, as does orange-violet to right flipper. Traced problem to 2J12 pin 1. Reflowed solder on pin to create reliable connection from relay.

After putting the board back, the right flipper would twitch but not work fully. I tried swapping in a new coil and discovered that the flipper had been installed too tight to the playfield. Loosened that.

Currently the right flipper twitches. I tried a variety of jumper wire combinations and I can’t isolate the problem with the left flipper. Maybe the next step is current measurements?