Have a problem with cassette 1 on a km2560, will be feeding paper as normal, and during a job it just stops and says add paper in cassette even though it has plenty of paper. Switched cassettes and pick-up assemblies and problem stays with cassette one. Connectors all fine and seated correctly and has latest firmware. If you open and close cassette when it stops it will carry on but says add paper again randomly, could be after 3 - 100 copies. Doesn't follow a pattern. Any help appreciated.