The problem actually have any. See here
PX 829B, Pumpenventil
or get out of the Medical Breich 2nd choice is a pair of pliers
Hello and 
here,
this problem sometimes appears.
The reason could be:
a) There are some depostits from old fuel inside the tank, which cover all surfaces. In this case the valve ist too lage in diameter to come throught the core dimater of thread.
b) The valve hooked at the lead gasket at the bottom of the pump
Some solution suggestions:
- put some solvet in tank, such like aceton, universal dilution, caustic soda .... to get rid off the depostis
{ in case of a) always clean the tank}
- bend a small hook with which you pull the valve out
- press (e.g. with a screwdriver) through the filler neck from the inside against the valve and turn it throught pump shaft
- grip it with a small plies and pull it out
Greetings Ruediger
Hi Mike,
What will tell the doctor if you ask him for a surgical scissors 
?
If you say you need the scissors for a Petromax lamp he once puzzled look 
.
PS: here in the forum.
Best greetings
Peer
Success!!! No need to explain to the doctor - I used a screwdriver to reach down through the filler cap and levered the valve out. It was very dirty so now I will clean the tank and flush out the deposits before going any further.
Thank you all for your help!
Kind regards, Mike
Good Idea !
Auf die einfachste Lösung kommt man immer zuletzt.
Das mit dem Schraubenzieher geht auch "Outdoor", wenn man mal das chirurgische Besteck nicht dabei hat! 
Gruß Jo
