It's a hardware issue, there are cables(wires) and plastic gears attached to the guides, if the gears slip, the size will never properly work, if you have a maintenance agreement, the techs can usually fix it in minutes, if you do not, good luck, it will be a lot of trial and error moving the gears.
We have a phaser 7500 DT printer. We constantly have problems with the printer not auto selecting the correct paper size.
We have A4 in Tray 2 and A3 in Tray 3.
Within Centre Ware IS under Printer Defaults, all trays are set to Dynamic.
Under Input Trays on Tray 3 I can select A3, A4, legal etc.
Under Tray 2 I only have to option for auto sensed or custom. There is no A4 on the list.
The guides are correct on the tray, we have A4 loaded in portrait mode. If i try auto senses it still picks up the tray as custom and not the correct setting of A4. I havent even got any default paper formats listed.
Printer is on firmware