By request, I’ve spent five minutes in looking at Kick N Run / Mexico ’86 comms for 4p mode. Actually got something…

…but the major problem is that this fix breaks the normal 2p mode. I wonder if I’ll find a solution for it…

*update* after trying everything I think that the most plausible option is that the reset line for the communication cpu is directly hard-wired with the dip-switch that controls the number of players, but I need to prove it…does anybody kind enough could send to me some high quality pics of this pcb, component and solder sides?