So I just finished the cap replacement mod. Sound working great crisp and clear.
I replaced all the caps on the main board with correct values and good soldering, but my screen is still nastily washed out. Is this normal? It's a minimal improvement from what it was. I was hoping for night and day.

I'm going to go looking for some schematics and see if there isn't something else that could be done to help the black levels...

You aren't going to get "night and day" improvement on the GG screen by replacing the caps. Even at its best, it's a poor screen that has always looked washed out. You can get a bit more improvement with an LED mod, but for the improvement you're looking for, it sounds like you want to do a total screen replacement.

no, i believe you still have to figure out the caps,(imo) did this on nomad, and it went from complete white screen to a really nice video image..keep searching for answers.. i have heard gamegear have several caps that need replacing..good luck with your project.