HI Jim,
The cam can move out but still be engaged with the plunger (couldnt think of the name of it last nite
)
As it moves towards the cover it may slip past the wee peg that limits the advance/retard range, and so the timing may be out in this position
Push the camring fully home in mid position, this will ensure it goes in correctly!!
The end cover is all that holds it in place
Sometimes the limiting peg can be damaged or bent!! if this happens symptoms like you are having can occur
ie, losing sparks on one side when the lever is towards the retarded position
(Its coming back to me now ???? ????)
Some time ago I had problems with a K2F similar to yours,
The peg which is factory set and a rivit fitted at the end so as you cant fiddle with it
in the retarded position the points were opening when the brass segment of the slipring had passed the pickup brush
I carefully drilled off the rivit head and was then able to turn the screw with the peg which is eccentric to the screw
to advance the camring.
I set it the same as another K2F I have and glued it in place with some araldite
This mag had a steel points plate, and when compared to a brass plate setup I found that the points opened sooner
in relation to armature position.
To "fix" this I filed away the leading edge of the fibre block to delay the points opening so as to make it the same as the brass points plate
Then the mag has to be retimed to the bike!!
HTH
John O R