Looks like I was wrong on this one
The manual is called "Masport Rotary Mowers Servicing Manual " and some very nice person has uploaded to
Manuals library .
A little more complicated than I was remembering but basically the same.
'Heed the warning about draining the oil & fuel before you start
I tip all push mower on the catcher flap to avoid these problems
So take the guard off the the transmission then sit the mower on a crate with the handle bars on the ground held down with a brick or similar .