shift problems

[rogcol1023]

I have a model 609. with engine running can't shift. Have to cut off engine , shift, crank. Anyone have an idea what could be to problem

 

[bertsmobile1]

Welcome.
I am a little confused here .
What do you mean by shift ?
AFAIK that model came out with a variable speed , controlled by a single pedal which is depressed to make the mower go faster .
Apart from that there is a single shift lever that selects F - N - R
The latter should never be touched while the mower is moving and if you can not shift it with the engine running then the clutch needs adjusting to put more slack in the belt when the brake pedal is depressed.
IT will not change unless the brake pedal is depressed.