@Caretaker, i just found this on the old FOC-U forum, i was correct in saying you have the old 9mm nut on your bike, and not the 12mm modded one.
Fowlers should be well aware of this by now, and it should really flag up on their computer about this issue!
It's only a few quid for the modded nut, but it's worth changing for peace of mind in my humble opinion.......:
".....ok got to the bottom of this, spoke to the dealer earlier in the week and spoke to another parts man who confirmed his mate looked up the kit (90891-10124) but ordered the 2 separate parts. They came in 2 bags, the washer being 90215-21290 and the nut 90179-18020 and of course this was wrong.
They then placed an order to yamaha just for the kit number 90891-10124 which turned up today in one bag with the correct modded nut.
The conclusion of this in case any one else has the problem, make sure the dealer orders the kit....."