Originally Posted by ywouldi
Ahh, great, thanks both. Now I understand why I shouldn't touch it, I'll just do the brake cam o-rings then and see how it goes. I think it needs a new breather/filler cap as it has been painted which I gather ca cause it to over pressurise and force oil past the seals as well, although I don't think this happens in this case as it's not been ridden at all recently.
You can test the breathing on the filler cap by blowing through it.
If its blocked the dome is a press fit on the riser.
You can remove the dome with a pair of pliers if you need access to clear a painted blockage.