I recently bought an NES Advantage. I don't think I had touched one for 20 years. Unfortunately, it came to me in somewhat rough shape. The A button didn't seem to work, and the knob above the B button turned only with some effort. So I decided to disassemble and clean it, keeping an eye open for potential problems.
Things you'll need include Q-Tips, isopropyl alcohol (I'm using 91%), a phillips-head screwdriver and a toothbrush. Depending on what's going on inside the Advantage, you may also need some vinegar. I used some apple cider vinegar.
Oh, and you may want a Hazmat suit and check that you're up to date on all your shots. You never can be too careful when cleaning game controllers.
Step 1: Open it Up
First remove the turbo knobs. I was able to pull them off using only my fingers, but you may need pliers. Be sure to wrap the knobs in a cloth or something if you do so that you don't damage them.
You can see in the picture that the B button knob is very rusty. Not a big surprise.
I used needle-nose pliers to unscrew the nuts. There are washers as well. Set them aside. If they're rusty like mine, we'll come back to them soon.
Unscrew the ball knob on the joystick.
Next, flip the Advantage over. You'll see two screws — one centered at the top, the other at the bottom. There are actually 6 screws total. The other 4 are underneath the rubber pads. I just used a pocket knife to peel them off. They were disgusting as well. Anyway, unscrew them all and set the screws aside.
Now hold the Advantage shut, flip it over and set it down. You should be able to pull the top off.
The inside of mine looks fairly bad. There's a large rust spot on the base and there's grime or something all over the inside. You can see grime and rust on the potentiometers.
Someone obviously spilled something on this. Let's clean it up.