Neo Geo AES graphics problem

In a garage sale I've managed to get a Neo Geo AES console but it's not working correctly.
It looks like one layer of the sprites is not working. I've tested several games (which work correct on my other AES).

Things I've already tried :

* Cleaning the cartridge connector
* Checked the cartridge connector with a ohm meter on the solderpoints on the motherboard

Youtube video of the problem :
http://www.youtube.com/watch?v=nyyBesBdV98

 

It's a problem with character ROM graphics since the Static Layer is showing up fine. I don't know what could cause it if you are sure the contact points are clean and making electrical connections. But someone probably has an idea. Did you try a variety of games, both large and small, to see if ANY character graphics show up properly? Remember, character graphics, not the static layer used by the Credits or overlay display for energy bars and such.

 

The first game I've tried in the video was Fatal Fury Special and the second was Last Blade II. So yeah one smaller game and one bigger one...