As per title, my rear wiper 'works' sort of It will park itself at completely random positions,i have; replaced cog in motor,tried repositioning on spindle,just wondered if there is a 'park' sensor that is at fault ?

Mine did that until it stopped working completely whilst in the 6 '0'clock position. There are loads of threads going detailing fixes, but I just bit the bullet and bought a new motor. It was easy enough to swap and I changed the high level brake light at the same time as that was also acting up. QUID FACIUM TIBI
ANTEQUAM ALIIS

2003 TD6 VOGUE Zambezi Silver
tows 2006 Lunar Delta 540/2

yep,i suspect a new motor required, i have read most of the search results and have tried most of the suggestions to no avail.
I think someone mentioned a sensor that parks the blade hence the post