Ricoh G133 Service Manual page 913

Paper End Detection (Paper Feed Side)
2.6 PAPER END DETECTION (PAPER FEED SIDE)
The paper end sensor 1 [A] detects when copy paper in the paper feed side runs out.
When there is paper in the tray, the paper pushes up the feeler [B] and the actuator enters
the sensor. When paper runs out, the feeler drops in to cutout [C] and the actuator leaves
the sensor, and the machine detects that there is no paper in the tray.
SM 19 B801