Sounds like a problem with the 43v. I would start with resoldering J3 on the SD board. Also check the jumper on that connector. Nest check the connectors on the rectifier board. If there is any evidence of burning they should be rebuilt.

There is no computer or circuitry control of the flipper in this game. The cabinet flipper button delivers a ground via the button. If the flipper sticks up and it's not a mechanical issue it can only be due to a stuck button switch or ground short.

I have a pinball electronics NVRAM. The exact one in the picture. It's a legit company.