Sega Hang on bad Ram

[Filmmaker5]

Hi guys. My first post! John inspired me to start collecting. One of my first games I got was a Hang On. It didn't work at all. I got it working. Found out someone unplugged the monitor and a 5 amp fuse was blown. Thought I was golden. Not so. Problem...
It doesn't steer left or right. I checked diagnostics. It shows that the potentiometer is working, but they were weird #s.  I did a memory check and it says one ram is bad on IC1. Could that be why it won't steer? I got a replacement chip and it had a socket.. no change. Looking further at the boards, there is another board with an IC1 on it. That one would require resoldering. Any help would be appreciated. Anybody have ideas?  How do I find out which one is bad? Which IC1 chip?  Thanks  in advance.