I have a couple nintendo's.  One that blinks and one that don't start up at all.  I have tried using a new 72 pin in the blinking one.  Is there anything else I can do to try and fix them.

Yes I was also using clean games that worked great in my top loader ;)

Did you clean the connectors that attach to the 72 pin connector? Those get dirty as well.

Since you have two NESes, might I suggest you disable the lockout chip on one of them?

What would disabling the lockout chip do and how can I do it 8-)

It's either the third or fourth chip from the left.  It prevents a lot of games from working, and makes it a LOT harder for the games to load.  Someone should confirm which chip it is, but you should look it up too.

Disabling the lockout chip did wonders for me.

You can also push your connector pins together as well. Doing both of these things will make your system a lot more robust.

For the one that doesn't power up, if you have a multimeter you could check the 7805 regulator.  When powered, it should have 7.5V or higher on the input pin, and about 5V on the output pin.  Check to see if there's a short between 5V and  ground (when not powered).