I just pulled my NES out of the closet after 10 years to find it only playing games in Black & White...no color at all!

Here are the facts:
#1 - It works great otherwise and used to display color fine.
#2 - I have cleaned the contacts on the system and games thoroughly.
#3 - I have tried AV and RF both with the same result.
#4 - I have tried numerous different acs, avs, rfs with the same result.
#5 - I have tested numerous games on different tvs with the same result.

I don't know what else to do.

Please