Rock-ola 474

I have a Rockola Sybaris 474 that refuses to select a record.
I can select any record and the inner double ended selector arm will rotate stop and knock a tab down, the other ,single ended sector arm (on the outside) then rotates but does not stop.
On each cycle it either jumps the tab or on the next rotation it will momentarily stop and the mechanism/gears only just begin to move and then stop with the arm starting the cycle over and over again.
This happens on all selections
I have cleaned and checked all contacts on the inner arm and outer arms, including the small tab contacts.
I have also cleaned and checked contacts at the carousel end.
I can freely move the pick up arm manually through its cycle by turning the exposed armature shaft and there is no tightness or resistance, I have also gently heated to soften any hardened grease,to no avail.
Any help greatly appreciated.

Regards
Stewart

Hi
Is the same for A and B sides?
Clean the slip rings on the read out side of the wobble plate, if dirty might be preventing proper contact
Check micro switch no. two (behind the tone arm), also check the usual plug connections and clean relay contacts in the control box under the chassis
clones

Hi Stewart,
My GUESS would be ( if not the MicroSwitch) the "locking relays" in the junction box under the mechanism base. I would remove that box, and physically check the "locking" function. Ron Rich