A bright light above can change the size. There is a shade kit that can be put on the sensor. Another thing that can be done is putting a shim inside to keep the guides from moving further than 11".
Technician came onsite and insists that the secretary is accidentally waving her hand or papers over the sensor on the document feeder. She has apparently came across this issue at other sites as well. We'll be more vigilant and see if that is the cause.
Sounds like a document handler issue not detecting the size of the originals. Have a tech look at it. Make sure the guides are tight. Sometimes the guides can loosen up with a big stack of originals.
Upgrade the firmware and hope, because if that doesn't resolve it an Altboot will be necessary as it would appear a clone file was used across similar devices at different firmware levels, and if that is the case an Altboot is the only way to fix it (Complete loss of settings)
Copying sets of documents with auto on and all documents are letter size. Legal size paper will be pulled randomly for one of the sets. No apparent reason. Xerox suggested sensors in paper feed tray were being triggered somehow, so we were cognizant of the sensors and careful. Still happens. This has happened consistently with this 7970i copier although it hasn't happened at all on our other two 7970i copiers. All set up with same clone file. We've confirmed the paper sizes in the trays. Any suggestions on what we should look at next?