Many thanks guys for the suggestions...
Peter came over on Sat arvo and we double checked everything. Arms, pivots, gears, rotors, cranks, motor, terminals, wires, linkages...

Everything looked spot on.
Looking at the manual and Peters EK it looked like the crank shaft position is at about the 10 o'clock position. When we positioned mine at that spot and turned the wipers on the crank shaft wouldn't take up immediately and so the wipers didn't move immediately. This got us thinking that the 'park' position was out even though when the wipers went to 'park' at the horizontal position.
Looking at the manual on page 12-94 point number 17 it says "To adjust the parking position of the crank rotate the head of the hexagon pin as required using a 5/16 .in A.F. spanner, Fig 12F-11."
You can see the hexagon pin in the pic below.
Using some strips of masking tape as a guide we rotated the crank so the wipers moved up about 45 degrees. I think I turned the hex pin about 1 and a half turns approx. As you turn the crank you can watch the wiper pivot move into position. We turned the wipers on and viola! Success.
I think I must have spent about 3 hours trying to work it out...

...with the last 30 seonds of roatating the crank actually fixing the problem.
Anyway I learnt something new which is what it's all about. Thanks for your help too Pete.
Stewart