DIAGNOSIS The tape-end optical sensor is dirty or blocked. It's a small, clear window inside the tape compartment.
FIX Remove the tape cartridge. Shine a flashlight into the empty compartment. You'll see a small plastic window with a LED behind it. Clean this window with a dry cotton swab. Blow out any dust. Reinsert the tape cartridge firmly until it clicks. The sensor should now read the opaque tape leader.
IF THAT DIDN'T WORK The tape cartridge itself may be defective or a third-party brand. The official SUPVAN cartridges have a specific black mark on the leader that the sensor reads. Some generic tapes lack this, causing a false empty signal.
HEADS UP Never use transparent or clear tape in this machine. The optical sensor cannot detect it and will always read "empty." It requires opaque backing tape.