My Haynes repair manual says 'lower the tank slightly and remove the filler
tube'. Unfortunately it doesn't say how to remove or reinsert the filler
tube and I am wary of pulling it out in case I never get it to seal again.
It looks as though the tube just pushes in with a rubber bush to seal it.
The alternative is to dismantle the bits of metal that the filler pipe must
get past if I leave it attached to the tank.

Has anyone any suggestions?

Thanks, Ted