Video was shaky, jitters and flips around a lot. To fix this solder a 1k Ohm resistor into place between the board video output and the Gonbes sync connection. I have also heard of people using a 8k Ohm resistor on the sync wire.
Using a resistor helped a lot!
Convert to better firmware:
https://www.youtube.com/watch?v=ZftKgnI0gvM
https://shmups.system11.org/viewtopic.php?f=6&t=52172&start=2880
GBS-8200
