Don't whack the camera! At least not first. With mine is was the tape, not the camera, that needed a whack. There's a little lever inside a depression in the back of the cassette. When the lever is pressed the tape can turn. When it's not the spools are locked in place. If that lever doesn't move the camera can't use the tape and it says to reinsert it. I moved the level with a pencil and heard a noise inside the cassette, which seemed to be the spool lock popping loose. It had been stuck. Then moving the lever again was silent, and the camera is happy with the tape again.
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