Strange neo problem

Ok, I got a dead neo sitting on shelves for quite a time now, decided to look back at it today and problem is quite strange.

Neo works "fine" except it don't display all "cha" graphics. Fix graphics display well (credits, push start etc...), music is also fine as well as gameplay. Screen is mainly black...

So what should I check first ? Sprite RAM ? Neo custom chips ? Got others dead systems to cannibalize from

May sound dumb, but did you try cleaning the cartridge slot? If not, use some Electronics Cleaner from Radio Shack on it.

Make sure to wait at least 24 hours before turning it back on though... just to be safe (and evn though the cleaner is supposed to be "no conductive", it's still best to play it safe than to kill another system )

Bad contacts would show corrupted graphics, no total blackout...

Is it like this?

On Bootup, NEO GEO is not displayed but MAX 330 blah is shown.

On demo mode, credit level blah is there but pic is missing.

In game like LB. Life bar and credit seen, but no charecter nor background?

If it is like above, unlikely dirty slot.

More like damaged chip...I have one like this and repairing it. I am looking at the slot connector solder as I suspect some trace is broken...could be chip too.