Infinite multiball is usually an indication of a ball trough problem. Moving a game would tend to exacerbate this, since the solder cracks on the connector, and moving always adds a little extra stress. Re-seat the connectors on the PCBs; this might work for a while. But ultimately the solder joints need to be re-flowed.

It's also possible that the optos are going bad, but that's usually not the problem. (I've had to do this on a couple of the games of similar vintage, but not my RCT.)