Ok, i'm back on this project. Thank you for the reply.
Are there assumptions in your reply however?
Is it necessary for the headliner panel to be removed to access this cable end in the cabin?
So far I'm driving a soft wedge up 7 in to remove the 8mm bolts.
Is it possible to unwind the drive unit from the back end of the cable in the trunk and not disturb the roof end of the cable?

From inside the trunk i don't see any problem with the cable end as it passes through the drive so my diagnosis so far is a drive gear.

regards,