Missing Right Half of Characters

[dr_slump]

Hi everyone!
New member here — long-time Amstrad user. I learned to program on a CPC-464, owned one back in the day, and recently acquired another unit that I'd like to use to teach my daughter how to program. :-)The computer is in generally good shape and basically works. It even loads and runs games without issues. However, there's a clear display problem visible on the startup screen (see the attached photo).
As you can see, the right half of each character is missing and is replaced by the background color.
Since everything else seems to work normally, I assume the CPU and memory are fine, and the issue lies somewhere in the video subsystem. The motherboard is a Z70200, MC0002D, with a Gate Array model 40010.
Before spending 40€ to replace the GA, I started checking the chips that feed its inputs. I replaced IC115 (74LS244), but that didn't change anything. My next suspect is IC114 (74LS373).
Before going further with the repair, I wanted to ask if anyone here has seen this specific issue before. I've watched several repair videos, but haven't come across this exact symptom.
Any ideas?
Thanks in advance!
—Paco

[salvogendut]

seems similar to this case 

[McArti0]

Has Games stripes too?

[dr_slump]

Yes, games also look weird with vertical stripes. Unfortunately, I didn't take a photo of the screen.

[McArti0]

373 works good. GA does not capture the second byte from memory in the video read sequence.

Try type CLG 3.