I have a RoadShow that I bought about 3 months ago. It works fine, no credit dots, no old battery leaks on the cpu board as I can see. I changed to three brand new batteries after buying it.

After about a month without problems playing daily I then renovated the pin room for ~two months were the game was never plugged in the wall.

Today I switched the game on again and the DMD warned about settings being restored to factory, had to re-set to freeplay, shaker strength and so on. After that the game plays fine again.

Tried turning it off, wait 10 minutes and turn it on again and settings were kept.

What could be the issue here? New batteries should hold the settings for several years right? The battery holder is the stock one (piggybacking to the cpu board on its own small board) and therefore I doubt it's connected wrong.

What could be wrong? Should I be concerned or just ignore it as a "shit happens" thing?

Thanks for all input so far. I will start with rechecking the battery holder, it's cable connections and change batteries to new ones once more.

Nvram is an option but then I have to unsolder the old chip and install a socket, which is a bit of a hassle so will probably be the last thing I try.