Toggling on the device causes a mechanical clicking sound somewhere in the device (other than the click from the power button) is this normal?

This is normal behavior. That clicking coming from the inside of the instrument's chassis is a relay/transmitter component installed on the PCB which is delaying the activation of the audio output of the Tracker/Play device so there's no loud pop noticeable on your speakers or headphones on the on/off toggle. That prevents your gear and your ears from harm.