2 NES, different colors

[vernon_r]

Hello everyone,
So here`s the deal. I bought a second NES because my first one rocks. I thought: "It might broke, so I better go get myself a replacement". The fact that the system has survived twenty something years didn't really matter then. Anyway, I just got it from the US. It is an original system in its original box. It even came with the original printed manual! It doesn't work everytime, though. 3 out of 5 tries are either the gray screen or the flashing screen (I also get a "reset every second" screen, so the game starts over and over, showing the first second of it). I'll have to change the 72 pin thing, that's for sure. Now here's what happens when it works.

...The second NES I bought has darker colors! I thought something was not working properly, but in fact, it does work (when it does). It's not pitch black or anything, it's just slightly darker than my other NES. I checked it as well as I could. Opened the thing and there was nothing obviously broken or damaged. The only difference I could notice is this: The one with the darker colors has this number in the silver sticker underneath: "N0067614" and the one with the brighter colors has this other number: "N30398980". I'm no Einstein, but I figured that the one I recently bought, the one with darker colors, is way older than the brighter one. Am I correct? And if so, could this explain the difference between the two systems?

I should say that they are both MODEL NO.: NES-001

If anyone has a an idea, please let me know.
Thanks,
Tom