"I have a Brother 470 FAX machine that appears to have a broken micro-type switch that detects there is paper WITHIN the front feeder.
Also sometime it jams paper at the rear. It looks like it cuts the paper off (the copy or document report) a little short and the roll of FAX paper pulls it back towards the roll. Thus when the roller advances the paper next time it gets jammed as it isn't in the feed slot?"
(From: "NO UTN" (email@example.com).)
My experience with brother fax:
There are 2 detectors at the output of my Brother Fax, do not know type but it uses a roll of thermal paper.
Detector 1 simply uses an IR LED and IR receiver to sense the paper.
Detector 2 is on the cutter, when cutting paper the motor turns by means of a worm-wheel a wheel that moves a handle that lets the cutter move. On the wheel is a detection switch, there is a ring on the wheel from which one part is taken away to be able to detect the home position. If cutting starts the wheel has to be turned in a maximum time, if not the wheel is turned back and cutting stops. The Fax gave and error message. Solution: put some oil at the motor and it works again.