Thanks Guys...
"Is the missing sleeve that shiny metal tube just below the gear head in your picture?" - Yes that explains it now.
There is another bit that covers the whole area (I assume to protect the seal) which mounts on the output shaft, but obviously a bit too much grass had got through and wrecked the seal.
Taking off the three phillips head screws just removes the cover plate and doesn't expose anything else (tried that the other day).
Looks like Bruce's picture is spot on, need to lever out the seal to get at the circlip, which is what I was going to try next.
One last question...the picture says to fill with grease...Grease or Oil and does it need to be anything special or will high temp bearing grease suffice?
Thanks again.
Chris.
