Carefully check the condition of the parking brake parts.
If a break or rubbing of the wires is detected, replace the cable with a new one.
Make sure that the sector teeth and handle latches are not damaged; replace worn parts.
Check the condition of the spring. It should return the lever to the lower position.
Check the condition of the rear cable sheath and the fastening of the lugs on the sheath, and also make sure that the cable moves freely inside the sheath. If the sheath is damaged and the lugs are loose, replace the cable.