Usually dirty connections on the rom chips, edge connector on the pcb. Usual practice here is just do some re seating of the chips in sockets and a pink eraser cleaning on the edge connector. Does kind of look like a ram issue though..
If you do that make sure it is zero residue and make certain it is dry before you power up. The main connector on the edge of the pcb is the one that you use the pink eraser on and make certain that none of the pink shavings gets left behind to haunt/taunt you later. I suspect it is a connection issue and if you leave that game on for about and hour or two it will either 1) get much better or 2) get some worse. The Rom chips are what usually gets pulled and legs cleaned but I have seen and like for a field check, Just pull up the rom chips a bit then push back into place; CAREFULLY.
I don't like the spray method much but if you do go that route, remove the pcb and hold it in such a way that the spray will run off the pcb with the junk. Let it dry and re install and take pics before you remove the pcb so you know how the connections go back.
Definitely replace your interconnects between boards.. I'd say they're probably the main reason for video glitch issues. Fixed my vid glitch issues on my spy hunter which looked pretty damned close to what you have.
Definitely replace your interconnects between boards.. I'd say they're probably the main reason for video glitch issues. Fixed my vid glitch issues on my spy hunter which looked pretty damned close to what you have.