Just found the cause of the "clonk" on LH wiper arm
Attachment:
Wiper clonk April 08 002.jpg
The casting has broken and the spindle "floats" on the LH arm ..it clonks when it does the return from full sweep.
Attachment:
Wiper clonk April 08 001.jpg
I've got a replacement linkage coming,,,,for resaons only known to the wiper engineer Helmut Head

.........there is an M5 bolt which is a complete pita to get at, behind the LH spindle. apart from that not a bad job.
Good clean up around the scuttle area, hovered all the leaves and degreased the area.