Been working for months on a 69FJ40. Time spent correcting a lot of age and PO issues. Today I had the battery disconnected so I could finish installing new fuel tank and remove the rear heater. I reconnected the battery. When I turned the key the engine cranked but wouldn’t stop when I turned the key off. Disconnected the battery, lubricated the ignition switch but same problem when reconnecting the battery. Tried a different key to no avail. My gut tells me the ignition switch has failed. Am I on the wrong track. Thanks in advance.