There are several solutions to the head shaking posted here: PiDog Servos shaking - #15 by DarrenL
Personally I found a rubber band does just fine as shown here: PiDog Servos shaking - #12 by shanbady
The sound issue may be just due to having the wrong default output set on your pi. Install alsa utils via “sudo apt-get install alsa-utils” and then see what the default output is “aplay -L”. you can search online on how to change that to the use the correct output device. you can test it works with “aplay ”