Sure can be frustrating.....mate of mine bought an Addams, and we installed some Cliffy protectors. A few days later he calls me to tell me that the game keeps going into multi ball without qualifying. So we work out that all the switches in that row have flaky operation...so I think it's a flaky switch or diode....after an hour or so of testing and eliminating, his wife (her game) says she thinks it's something to do with the protectors as it started soon after....turns out one of the target switches was close to the Cliffy, and touching intermittently!! What a pain! Should have thought of it right away being the most recent change to the game........