Hi Frank,
Unfortunately there are no diagrams available for these mowers. Atco parts books did not become pictorial until after WW2. With the clutch, the spring causes the cone to be engaged when there is no tension on the clutch lever and linkage, i.e when the clutch lever is pulled in it disengages the cone. When the lever is pulled in (towards the handle bar) the yoke should come up to the collar, engage and withdraw the cone. If the yoke is not reaching the collar, then have a look at whether you can adjust the length of the linking rod that goes between the clutch lever and the yoke. It is threaded at both ends. From memory, these mowers do not freewheel backwards.
Hope this helps.
Kind regards,
Sir Chook
