I got a Lightning Fighters PCB with GFX problems. As you can see, major colors and layers issues:

1) Probing the Konami 053251 custom chip revealed some weak signals on a few pins. This chip is a priority encoder, it deals with colors and layers and seems to be prone to failure in more and more boards of that generation. Unfortunately, you have to find a donor board of the same era to get a working one (good thing anyway is that it is used in a pretty good amount of Konami games).

Here is the result after swapping it with a good one:

2 & 3) Colors and layers are now fixed but we have some jailbars on sprites. This looks to be a sprite’s data issue. Probing the mask ROMs revealed missing signals on a few data lines for 939A05 and 939A06 ROMs. I replaced them with two burnt 27C400 EPROMs. Board is now fixed:

Here is an overview of the chips I had to replace on the board: