First Pin, First problem. I got this Firepower 2 last week and after a few days the credit button stopped working, and upon further investigation found the entire row wasn't working. Same problem as seen here - http://pinside.com/pinball/forum/topic/switch-matrix-question-williams-system-7-firepower-ii
Turned out the white wire on the credit button was just about to fall off, and in fact when i touched it it did fall off. I soldered it back into place Bob's your uncle I was back in business. After 2 more days, same problem. Checked the soldering, looked good, wiggled the wire a bit, button started working. Next day, same problem, no amount of wiggling fixes it. I removed the solder, and tested it before I resoldered and everything was fine. Soldered it back up, and it doesn't work. Removed all the solder, and now maybe 5% of the time when I hold the connection manually i can get it to work. I'm out of ideas, and sick soldering in this tiny corner. Any ideas? I'm stumped.

switch.JPG

Yeah, the solder has been removed from the top joint in the picture, because the button wasn't working after I soldered. I think I found the problem, replaced the diode.