RE: Okay, who's the Kraft radio guru?
Yes, you can take out the old batteries and make new packs that fit in the same location.
Servo chatter or buzzing? In a word, DEADBAND. The newer servos have a pretty tight deadband for higher resolution. So they do make more noise and eat the batteries quicker. Even the cheapest servo from the name manufacturers is better than anything from 25 years ago. And the good servos today are amazing.