what I have found on the web ( bedankt Jan, thanks to Jan for the foto's ) to change the O rings on the throttle shaft so far is:
get a 1/4 sae 12 sided spanner or socket to get the bolt out, zie foto2.
Take out the bolt to be able to get the shaft out, foto3
foto 4 to see the 2 O rings on the shaft to be replaced
Take out the antistall body part, after marking, measuring to get it back in the exact same place later. Loosen the locknut and turn the bolt all the way out with bleed screw and locknut in place. foto 7
push a pin or something into the pump body to push the spring? down, to be able to get the shaft back in. foto 5.
and bingo, just make sure you mark everything to go back in the right place and the Pull to Stop kabel has to be in the Run position.
foto 6 is all the parts
I have not tried this yet but will be after the winter layup
here in holland
. Also taking the manifold off and cleaning
the lowline heat exchanger
the whole sytem out.
hope this helps someone else having the same probs I am having.