When power is removed the Magnalock must release. If internal circuitry were to fail completely, the lock would only exhibit "stickiness" at a rough level of 5 pounds.
First, make sure that power is being removed from the Magnalock by the control device using a meter. If voltage is not dropping to zero check your control switches and wiring.
Second, check the face of the Magnalock and the strike plate for foreign material. Any material found should be removed using a piece of cloth and a non abrasive cleaner.