Tried to clear windscreen on Saturday, wipers stopped vertical position,
ive disconnected the new lucas motor from the linkage and tried it out withno issues
Thing is the linkage seems to be jammed solid
Any ideas why?
Im hoping the dash gets to stay on for fix

Could be a seized wheel box (behind the wiper spindles)

Just remove the top of dash

bolts/screws near glass (including air vents), and under front edge. Heater controls and dash binacle

Buster's photo guide should help

http://www.landyzone.co.uk/lz/f41/wiper-boxes-cable-renewal-99743.html