Originally Posted by Billy T.

It sounds like you have digital servos, which will make a digital buzzing sound due to the circuit always trying to maintain position. A couple of questions to help us help you.

1. What servo model is it?
965 mg
645mg
945 mg
2. Are both servos doing the same thing? Yes. I ask this because to have 2 servos "fail" in the same manner is very unlikely, which would then lead us to look more in to the installation and powering of the servo.

3. What are you powering the servo with?