Right, so I assume its a punto one then?
Have now opened up the front panel to investigate further. the problem is probably not related to the ribbon cables from the main unit to the front panel ( but they do still show signs of damage from even light use). There is another cable inside that attaches the screen onto the board for the front panel that is almost definitely the cause of the problem.
The Horizontal lines are dealt with by nice conductive rubber 'zebra' strips which don't seem to cause a problem. The vertical lines are dealt with in a different way.
the connector for vertical lines is, according to an LCD FAQ i was reading, bonded on by a combination of heat and pressure on a conductive paste.
This unfortunately will probably require a specialist tool to fix
:-(