Gecko power surge at shutdown and reduction ratios

Hi Group,
I'm running a couple of servos ( not connected to the lathe yet ), and
I noticed the servo running through a Gecko 320 buzzes a fair bit when
not moving but the main concern I have is that when I switch off the
controller, the servo spins for a second as if a capacitor is
discharging or something. It doesn't make any difference which servo I
use. This would move the Z axis on the lathe about 2" in a random
direction. Has anyone had this problem ?

Just a quick note about my "reduction ratios" posting a few days ago,
I ran the servo off 24 volts ( truck battery ) without connecting the
encoder and it only does about 350 rpm flat out,with a fair amount of
torque, so i'll see how it goes direct drive @ 15mm ( 0.590" ) per
rev.
Thanks for everyone's input so far.
Regards,
Glen