[Pamphonica]

Avo movements should be well damped when the switches are in the Off positions. But for another test to see if a movement itself is open circuit, locate the leads inside that go to the movement and short them out with a croc-clip wire.
If the movement is still swinging very loosely when the Avo is moved about a bit, the coil is probably open circuit. If the movement now stays close to zero there's probably a fault somewhere in the switching or cabling inside. Mk5 Avos have a flexible pcb-type cabling system inside that can go open-circuit at the ends or crack somewhere along a track.
Good luck
Jeremy