On your mower the whole system works backwards.
The PTO lever pulls against a spring when disengaging the blades.
Over time all the linkages flog out oval so the lever does not move the deck foreward far enough to give the belt enough slack to allow the blade brake to stop the blades turning.
If the belt has been smoking, it will now be wrecked and will need to be replaced but keep it for that "emergency spare "
Follow the PTO lever back and you will see an adjustment on it.
yours need to be adjusted to push the deck further foreward when in the dissengaged position to give the belt some more slack.