The two most disgusting things in the world are remote controls and video game controllers. I'm not sure which is worse. You can't always tell until you take them apart. Seriously, eww.
But some controllers have been around for a long, long time. The ColecoVision was released in 1982 and discontinued in 1985. That means that any official controllers out there are 28-31 years old. If they haven't been cleaned (and honestly, who cleans their controllers?), they're probably pretty gross by now. And let's face it, they pretty much combine video game controllers with remote controls. So let's clean one.
Step 1: Survey the Grime
First, let's take a good look at the work ahead of us. There's likely a lot of gross stuff all over the controller. Much of it is dead skin cells. Perhaps some of it is soda. Much of it may be cheese. Who knows. Give it a good look over. Then call your mother and tell her that you love her.
Step 2: The Equipment
Okay, now that you know what you're up against, gather your tools. You'll want a phillips head screwdriver, some pliers and a toothbrush. Mine's electric, because I'm fancy. Note that this is the equipment for the best case scenario. If your ColecoVision controller is flaky or unresponsive, you may need to repair it, which is much more involved. This instructable will not cover repair, but I may make one later on.
You'll also want some dish soap and a container of some sort to soak parts in.
Step 3: Disassemble
All right, let's take this sucker apart. The ColecoVision controller is a little odd. First, it's got a spring under the joystick. So when you remove the screws, you'll want to hold the controller shut or else it will open up quite dramatically.
There are five screws. Remove the outer four. The middle one actually holds the weird plastic d-pad-like thing in place, not the controller itself. Remove it now or remove it later - it doesn't matter.
Remove the top. Optionally notice how gross the keypad likely is.
At this point you may notice that the controller cord is tightly locked onto the lower half of the body. Extending from it are a number of cables that are attached to the circuit board. Depending on the model, they will either be crimped or soldered on. I've only seen them crimped on. Note their order. Take a picture and write it down. Using some needle-nosed pliers, pull them off. Then rotate the cable 90 degrees where it's locked in and carefully pull the whole cord out.
Step 4: Soak the Parts
Now soak the non-electronic parts in warm, soapy water. Be sure to remove the side buttons and soak them. Also remove the d-pad thing - carefully push it out from the other side.
Once they've soaked for a while, pull them out piece by piece and rinse them off. Then scrub them down with your toothbrush under water. Set them aside to dry.
NOTE: You may also want to soak the cord. I put the middle part into the bucket. It was pretty gross. See the pictures to see what I mean.
Step 5: Check Your Connections
Now is a good time to look over the main board. If you've ever taken apart a modern controller, you may be surprised by the directional controls on a CV joystick. There's a thin leaf of metal that gets pushed down by the joystick in each of the four directions. It's not fundamentally different from how modern controllers work, but it is much more flimsy. Those leaves tend to split and crack, especially over 30 years.
I was lucky with this controller and it was in good shape. If you're not so lucky, you may try soldering the leaf. Or you may want to attempt a large mod and replace them with microswitches or the like. If you do this, please let me know! And/or make an instructable. Seriously. I have some damaged ones.
Step 6: Clean the Keypad
Now's also a great time to clean the keypad. Trust me, you want those other parts to soak for a good while. Dip some q-tips in some rubbing alcohol, wipe them off, and go to town on the keypad. Seriously, it's gross. I've included a nice pic of the q-tips.
Step 7: Wait for it All to Dry
Here's the boring part. Wait for the parts to dry. You can wait for the surface-area moisture to dry then use a dust can to blow the water out of screw holes if you're impatient.
But seriously, make sure the parts are all dry. Then go over them with your toothbrush to get rid of any lingering junk. You might be surprised how much gunk is still there.
Step 8: Reassemble
Put it all back together and screw it shut. Play some Pepper 2 or something.