Brother HL-1070 - B/W Laser Printer Service Manual page 178

Note

If the multi-purpose sheet feeder runs out of paper when you try to
print, the Alarm and Paper lamps blink to alert you. You have to
load paper in the feeder and push the panel switch to cancel the alarm
and continue printing. If paper jams in the printer, the Alarm and
Paper lamps also blink. If the error is a paper jam, clear it referring to
"PAPER JAMS" in Chapter 6.

When the rear sheet feeder 2 runs out of paper and there is paper
loaded in the front sheet feeder 1, be sure to remove paper from
Feeder 1 temporarily (
Fig. 2-7 Loading Paper in Feeder 2
) and load paper in Feeder 2. (
2–7
CHAPTER 2 PAPER HANDLING
)