Some questions answered...
BOAC
What actions are required to move the AB 320 T/L from 'CLB' to 'IDLE'? Is there a latch that needs to be released or should it be a straight easy movement?
No latch, you just move them smoothly back to the Idle stop. It is easy to get a T/L out of a detent.
How is reverse actuated ie what is the actuating mechanism on the throttle quadrant?
To get from Fwd Idle to Reverse Idle you lift the reverser latching lever - this sits below your finger ends on the forward face of the T/L. Lifting it allows the T/L to move back beyond the Idle stop. There is not a separate reverse lever.
How is reverse N1 adjusted?
By moving the T/L back - airbus SOP is either Idle or Max Reverse.
Is there any mechanical 'drive' to the T/Ls in any mode?
No drive, no lock.. they are easy to move. There are physical stops at TOGA, and Idle; the Idle stop is pins (IIRC) that are lifted by the reverser levers, and there is another stop at Max Reverse.
borghha
I m not a pilot but I think it s becoming more and more likely that the pilot put both TL at idle but for some reason decided to put only one engine in reverse and thereby inadvertedly pushed the other TL far enough out of idle to make the plane's logic prevent spoilers to deploy...
No guessing allowed .. The investigation will show what happened to the T/L .. but if both were at idle with the a/c on the ground then the ground spoilers would deploy instantaneously well before mishandling pushed a T/L forward.. your hypothesis does not stand up.
TP