There's two fuses for the radio. You may have pulled the memory circuit fuse. That is always tied in with other circuits that are always live, like the horn or brake lights. There should be a separate fuse for the radio's switched 12 volt circuit.
Regardless, the cassette player should have stopped when the ignition switch was off. I've repaired a lot of Ford's cassette / cd combo radios, but I've never run into a problem with the cassette mechanism in the cassette-only radios yet.
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Tuesday, March 1st, 2016 AT 5:33 PM