So I've been reading and reading, trying to diagnose and fix this problem on my own but I just can't get to the bottom of it.

When I turn on my BK2K, everything is fine for about 10-15 minutes. But then, the GI on the upper playfield will suddenly start to dim. This starts with the pop bumpers and the upper left GI and eventually (maybe 10-15 minutes later) includes the right side GI and top WIN lanes. The GI on the WAR lanes is not affected as far as I can tell.

I checked all the fuses, especially the ones on my interconnect board. I checked the connectors, on the backbox interconnect board and the interconnect board for the upper PF under the PF. There is a previous burn, which I think was fixed, on J710-9. See pictures below. This was there when I got the machine though.

The issue started after I wired in an extra spotlight for the left side of the upper playfield. It was fine for about a week and then this issue started. Since then, I removed the extra spot and re-soldered the connection at the socket I was using. The issue persisted even when the socket was disconnected. Should I try to clean it up more and re-solder again? See below.

When it works, the voltage is around 6.1v and when it drops, it goes down to about 2.8-3.5v.

This is my second pin and I definitely have a lot left to learn. I'll also say that the playfield and GI are all LED'd. Thank you in advance for any and all of your help!IMG_2340 (resized).JPG IMG_2343 (resized).JPGIMG_2344 (resized).JPGIMG_2349 (resized).JPG

This is the spot I got from Marco. Honestly, I didn't care for it because it's very difficult to remove the bulb since it's all one piece.

http://www.marcospecialties.com/pinball-parts/04-10094

I later ordered this one because the reflector is detachable. However, I didn't get to use it because I ran into the aforementioned issue.

http://www.marcospecialties.com/pinball-parts/077-5026-XX

Okay, thank you. So I measured from the transformer to the backbox interconnect board, through J6 and J9. Everything is around 6v.
When J9 5 & 1 (vio and wht-vio) get to the upper PF the voltage is at ~3v.

Does that mean the issue is between J9 and the upper playfield, the violet and white-violet wires?

Edit: Checked on these wires at the interconnect board under the main playfield and the voltage is normal, ~6.2v. Currently trying to trace the wires between there and the upper PF to find the issue.

What should the resistance be?

What should I look for if I pull all the lamps?