I know I’m reviving an old thread here, but FWIW, I just swapped a 2430 battery on X-Men (SAM) with the power off. No loss of data. I did it quickly…maybe 30 seconds max. Not sure if that mattered. This was a game I got recently, so no really high scores yet to worry about. Figured it was a good time to try. The battery (Energizer) was corroded and leaking btw. Maybe original? Idk. My Wonka (JJP) however, has instructions which tell you to swap the battery using a piece of tape with the power on.