Did you get this sorted out?

I definitely would run a switch test on all the switches, including the trough switches under the apron. Use a ball to be sure they are registering with it. If you use your finger and find a switch does not register until it is below the surface of the playfield, then a ball would not register the switch.

Were the red jumper wires already on the board, or you added them?

Can you raise the upper playfield and run the test again? I've worked on one in the past where the wires are getting pinched as the upper Playfield was lowered. I never was able to figure out which wire was but I had to bend them a certain way to make it work

Was that the switch test you ran in post #8 ?

Try unplugging the J1 and J2 you had resoldered. I don't think it has anything to do with the issues, but intestered in knowing.

That helps. Which board is this? The board under the playfield?

ok. With J1 and J2 unplugged, can you test resistance on the J1 board pins between pin to pin. Ex. pin 1 to 2, 2 to 3, etc.. If there is a connection between 2 adjacent pins, likely you have a solder bridge, and probably would on the connector on the other side under the connector.

If you don't get connection between any adjacent pins, plug J2 back in and retest J1 board pins.

Ok. I see something off on J2 pin 1 shows a wire, but the diagram shows it should be at pin 2, just like on J1. J1 colors all match to the diagram and J2 does except pin 1. My BK2K is on loan, so I can't check mine. I'll have to see if I can find a picture somehow. Pretty positive that J2 pin 1 needs to be moved to pin 2.

BK2K wiring - Copy (resized).pngBK2K Upper IC board wiring J1-J2 (resized).png

Yes. Yes. Just make sure when you do continuity test (beep) or regular resistance measurement tests, you do it with the game off.

Looks like I'll be around my game on loan tomorrow afternoon. I'll check out these things.

Ok. J1 pin 1 to 2, 2 to 3, 3 to 4, etc did not have any shorts between pin to adjacent pin. I tested J2 the same way and none of those were shorted either.

J1 and J2 both have no pin 2 and both J1 and J2 have orange wires going to pin 1.

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So to sum up, appears the BK2K manual is wrong as it shows J1 and J2 having pin 2 connected instead of pin 1.

I would remove J2 as well. Seems to be a solder bridge between pins under the connector. Once you remove J2, I would clean both sides of the board with a toothbrush and alcohol really well to get the flux off the board between the solder pads.

Make sure you retest the board again before installing new connectors.

Excellent. Good job locating your initial flickering GI issue. Enjoy!!