I didn't notice "slack" on the screen. Would it have said that before displaying the error code? I didn't bother looking in the viewfinder, it's been that kind of month with this rig. The camera has had problems ejecting tape. The last time it was stuck, the black flap over the tape was closed while the cassette was still fully inside the camera. The deck controls (PLAY FF REW, RET button) did nothing, as if the camera didn't know a tape was inside.
No, I didn't turn it off then on again