I have recently upgraded my AFM to NVRAM (my first WPC-95 NVRAM upgrade). I have upgraded several other WPC and WPC-S games before to NVRAM without any problems.When I ve installed NVRAM I did not notice that the game had the 62256 SRAM so I did not make the necessary changes to the CPU board to host a 6264 RAM (or in this case a FM1608-120-PG). After booting the game it did not boot correctly. I have performed the necessary jumper and resistor changes but the result remained the same (I have also put a 6264 RAM, but the symptoms remain the same).

When I power the game on it loops in the sequence:

On startup
1) led 201 and led 202 are lit (for appropriately 4 seconds)
2) led 202 is on, led 201 goes off, led 203 starts blinking (quickly about 5 times) and repeats this cycle a few times
3) I get two bongs while led 601 blinks 2 times
occasionally strobe lamp starts for a second and saucer shake coil fires.

The other sequence goes like this:

1) leds 201 and 202 are lit
2) led 3 blinks slowly 2 times
3) I get two bongs while led 601 blinks 2 times

I have verified continuity of the traces below NVRAM sockets and everything seems to be ok. I have also replaced S2 audio eprom on the sound board and I still get two bongs. If I put in another CPU board the game works ok.
I am out of ideas myself and would really appreciate some suggestions to help me successfully repair the CPU board.

Thank you for pointing me to the right direction. I have upgraded the game to NVRAM in two steps. At first I have just installed the socket and put the NVRAM in. The game did not work so I have removed jumper W3 and (I do not why) replaced the original 1k ohm resistor R93 with 1.5k ohm resistor. Today I ve replaced the resistor R93 with original 1k ohm resistor, but the game still does not boot and according to pinwiki there is a problem with game RAM (led 201 is off, led 202 is on and led 203 blinks two times and I get two bongs).
Is it possible that I have fried something by putting 1.5k ohm resistor instead of a 1k ohm one?

Thanks, I will try that. Unfortunatelly I have cut the original 256 out when installing the socket, but I have one in Safe cracker so I ll remove it from there and try it out in AFM.

I did put the 62256 SRAM from Safe Cracker in it and added the jumper at W3, but it still acts the same. So basically should I check the traces from top of the socket to their final destination?