Welcome to KLOV! NBA Jam is one of my favs so congrats on the purchase. As for the rom error, it's entirely possible that chip is just bad. If you look at the pcb there should be labels on the different chips unless they've fallen off from age. I don't know offhand what UG22 does, but it may just be one of the socketed program roms. Someone online can easily burn you a replacement and that may fix the problem. It's possible something else is causing the error besides that rom itself. Does the game play at all? For what it's worth, I have a Mortal Kombat machine that gives a rom error on but still works fine. I've read where someone else had the same problem, but the game worked fine.