Unfortunately, I didn't document the project at all along the way, so everything here is from memory.
See a couple of posts ago for the big parts you will need.
First, get yourself a BJ Bearytales. Now, you're going to want to field dress the bear carefully. The skin is attached to the body in some key places. I would start with a slit vertically up the abdomen, and then go across the neck. Be careful on the head. The nose and the ears and a few other places are attached to the skull. The tricky part is the back. The backpack is holding on the skin here. What you need to do is take out the backpack screws. The manufacturer thought it would be funny to use these annoying little triangle screws. I was able to get them with a flathead screwdriver; they're not screwed in too tight. (Don't be afraid to have fun mutilating your little friend; he would do the same to you if he got the chance)
OK, now you have the bear stripped. You'll see a yellow wire going down his left arm and around his hand. I wasn't sure what this was at first, so I went ahead and removed it. It turns out to be the antenna to trigger his hand accessories. If you plan to use the accessories, then leave it be.
If I remember correctly, the circuit board should be exposed now. You can unscrew it if you want and pull it off a little. Be sure not to sever any of the wires yet, you are going to want to keep track of which ones are which. I started by removing the skull. There are 7-10 screws holding the skull on, including two on the neck. Take all of these off. The last thing holding on the back of the head is a little spring clip on the neck. Carefully pull this back and remove the back head plate.
You should now see a green gear box. I don't think it is screwed on, but It is attached to the mouth, ears and eyes. I would first, move the ears out of the way (no need to remove them, just unhook them from the gear box). If you look through the eye holes and mouth from the front you should see how they connect to the gear box. Carefully slip these off the hooks using a small screwdriver or other small tool. You should now be able to remove the gear box.
Notice where the wires go on the gear box. Two of them attach near the bottom, and the other three attach near the top on the side. The two bottom wires drive the motor. The top three are for sensing the position of the gears. This is to make sure he doesn't slip a gear and stop mid-blink, horrifying your children with his half-blunk hollow eyes. You can remove the sensor circuit board with a screw-driver, I think. It is interesting to see how its set up. I think the middle wire is either ground or power and the other two are for sensing. I didn't use them for anything, but they would be extremely useful to get feedback from the head. I just didn't have enough pins on the Arduino to do this.
So at this point, I cut the head motor wires about halfway between the gearbox and the circuit board (to leave myself enough room on both sides to re-attach if I needed to). This time you can start to play with the motor using your own power supply. You'll see that if you run it in one direction it will drive the eyes and ears in a periodic cycle. That is, he blinks, he wiggles his ears, blink, wiggle, blink, wiggle, blink, ad infinitum. If you run it the other way he'll quickly run his mouth half-way and then get stuck in a horribly loud clicking lock-jaw position. They key to mouth is you run the engine a little bit one way, and run it a little bit back the other way. If you run it just a little bit it will keep the eyes and ears from blinking. I think it disengages them when you run it one way, and then reengages them when you run the other.
That should be enough for you to play around with now. I'll update more soon, including a picture of the original circuit board with a rough pin-out listing.
