I must confess a dirty trick.... my M50 process was delayed a bit as I am using an old Clutch Steer hull with modified heng long traverse. I used a turret lower from an old WSN T34 85 as the spacer and everything looked hunky---dory until the vehicle was buttoned up. The turret stuck at multiple points around the circle no matter how much I sanded and buffed the plastic.
I cheated.
I sprayed WD-40 on the ring from below.
No more problems.... for now.
(don't forget to wipe the excess off...)
IMG_7202 by
Ethan Dunsford, on Flickr