You can not use mechanical switches on the clock input without some debounce circuits.
A switch can bounce 2-100 times for every push and reelese leaving JK in either state.
A simple RC filter (100-330 kohms and 0.1 uF) can fix it BUT do not use a circuit from Thoshiba, NXP works! Texas?
Why not use a small uC and do all debounce in software? A small 6 or 8 pin.
Pelle