Rubbing alcohol can damage connector tips
far more faster, then water can. You only
need a hot water. Or better yet hot breath
and something super soft, like Steel Wool,
silk, or whatever Hanes is made out of.
The flat fact you need something super soft.
Alcohol whatever 50% is used for cleaning
Cds. A connector pin is not a cd.

The flact fact you need to do research on
cleaning computer components. I am not
talking about that spray in the can stuff,
that cause scratching between connectors,
something more official. Maybe something that
usted to be in hardware stores, but now you
have to order the stuff.

About the lock out chip? Why disabled it?
Did you try putting back the connectors,
before cleaning it first? You need the check if
the connectors work before you clean them.
Dusty connectors is usually the problem,
and when dust and water ( condensation )
mix it creates a sludge problem. Most people
keep their NES in a dusty area they think is gaurded
but it is not guarded unless the air is cleaned.

I have my NES from when I was three years old,
and I never ever used alcohol anywhere near it.
The last time/first time I tried and used alcohol
I damaged a SMB2 cart.

Their are tons of reasons why the connectors
do not work. I have a NES where the connectors
are not closed in tight.