Hi Brett,
When the display fills with lines, can you still play the game but just can't see the display? You may have more than one problem, I would measure the voltage on the back of the DMD. The power supply which drives this often require rebuilding or have dry joints on the back. For the memory problem, I would measure the battery voltage across the ram chip pn the main CPU board to ensure it is recieving the correct voltage. I can repair the boards for these games if you get stuck.
regards Derek
