Xerox 420dc " load bypas tray"

[axyun]

Customer called this afternoon and said they make a few copies and then the message to load bypass tray will appear in screen. Am I wrong to assume that the machine is detecting a different size from what is loaded in regular trays and so is asking to load bypass with a different size. Maybe if there is an original size sensor it is misreading the size of originals.
I didn't ask customer at the time as I had to think about it and was involved in something else at the time. Any guidance is appreciated. In meantime I will Frank

[adriansto]

Pull out the tray. It's a paper sheet on the sensors.

[axyun]

Thanks Adriansto. No paper blocking sensors. The "Paper Supply Status" screen showed that tray 1 was set up for #10 envelopes and Bypass tray was set up for 81/2x11. After correcting it would go back to that same setting after a couple of minutes.
I swapped tray #1 casette pwb with one from a pseudo tray and that took care of problem. Bad casette pwb. Frank