calvino:

Well, odds are, if you slow it down, you can quiet it down, and you did say its too fast, right? If you are going to mount something heavier on it (like a pan/tilt camera) you'll want more power too, and the simple way to do both is a motor swap.

If you open it up, compare the motors in it to the oners in your RC10. Same size, then its a 500 class motor. A good choice for hore power/less speed is one of the Integy lathe motors, in 45, 55 or 65 turn range. If its smaller, you'll need to take some measurements for us to see what size it is.

How's that for a start?