Black Tiger repair log

Some months ago I purchased from USA an untested original Black Tiger PCB, I was looking for it since ages because I had only bootlegs so far.For the uninitiated, Black Tiger (known in Japan as Black Dragon) is a 1987 platform game released  by Capcom.
PCB is a two stack one with a CPU and VIDEO board :

On first power up it turned out game was fully playable with sound but background graphics were wrong affecting also the priority with sprites  :

All the circuit that generates the backgrounds lies on bottom VIDEO board.There are four 27512 OTP ROMs storing the relevant data.Then, shortcircuiting some data/address lines, I could figure out that a 8K x 8-bit SRAM was involved too:

The background graphics rendered in wrong position led me think about an addressing problem of the above mentioned RAM.I figured out part of the addressing circuit and all was normal while checking it until I came across two 74LS273 @10F and 11H

Most of outputs of the two ICs were inactive while inputs toggling and clock present, here's a snap from a logic analyzing :

Once removed the two ICs failed the out-of-circuit test :

I installed round machined sockets and good ICs :

 This fixed the issue :

 I tested the game and no other problem was found.Repair accomplished.