I got this game for a repair:
The game had some background problems ( unfortunately I forgot to take a pic ) and a sprite problem:
The background problem was fixed reflushing the custom chip 56.
As for the sprite problem, after some time checking the part of the circuit responsible for the sprites, I found a couple of 6116 sram @D5 and D6.
One of them had some weak signals on the data lines and tested out of circuit it was confirmed as bad
After replacing the sram the game was fixed