vento 1995, drivers window (manual) jammed shut

[Pooley]

the drivers window on my vento 1995 recently just stopped working.
It is manual, and for no apparent reason now refuses to open.

If you giggle it a bit, it move a tiny bit, and the winder can be used to close it the last 2mm.

Have taken off the door panel ( a job in itself) and can see the winding mechanism, and have tugged a bit on the cables but there is not budge, and it is difficult to impossible to see any possible obstruction.

any suggestions