David_Moen,

Bill Mixon got it right on the control surface flutter, in another word the control surface vibrates/flutters at a frequency that is harmonic to it self or another component of the model.

"..........,but I don't understand the flutter thing."

Although it does not address counter balances per se, but this link http://www.airspacemag.com/ASM/Mag/I...FM/Hammer.html
would explain the flutter thing much better & there is a link at the end of the article that will take u to the movies of things that flutter in a real aircraft.

Hope this help
Hisham