the pinlock on my vac vault drawer is stuck. i can use the key to turn the lock mechanisma and the lock will fall downward about 1/4 - 1/2 inch but will not fall out of the recessed part of the vault drawer. i pull as hard as i can on the key downward but it will not fall. i can also turn the key and push the lock back up so as to relock the vault. anyone ever had this problem. vacs and locks approx 8 years old.