Clutch/Brakes/Shifting all in one can

[DblbarrelMower]

Hello! I own a older riding Murray that I really like. It will rooster tail (when I'm not here posting for help). Ive ran into a issue that I can't find an answer to so I come here hoping for alittle info. I am disabled so push mowing is out of the question.

When I push the clutch in the mower doesn't stop moving, it wont allow me to change gears. Ive included some photos that I hope will help with fixing this issue. Thank you in advance for your help. It is really appreciated!