Looking at the design probs the whole mechanism, you can get them for like 30 quid from a breaker on ebay, if you're lucky and you can swap a part over then you can just nick it from the used one. I can't imagine it's that hard to replace either as access is pretty good under that scuttle panel.
I've had my wiper arms off tons of times for various job but I never Torque that 13mm nut, just hand tight with a small quarter inch ratchet.
Thanks for the quick reply Clark.
I guess a trip down to the local scrap yard is due then. I'd order one online, but Ireland is pretty crap for online used car parts. And can't order from the UK because of ludicrous taxes and shipping time.
Hopefully I can separate the linkage, as that seems to be the only part I need.
Yeah I thought torquing it to 20Nm would have been more than adequate, only to have it start flinging itself at the other wiper arm less than 10km later
Lesson learnt though. Don't torque wiper nuts.