Although the original posting of code E-01 is a mechanism based fault, the standard "safeguard mode" without an error code and something seen by many can be caused by a multitude of reasons as its only a "blanket" fault warning, and can only be considered as such as it doesnt pin point the fault area. However on the "D" followed by three digits models the reason can occasionally be that the mechanism has not returned to its correct stop position after having carried out an operation (load / unload etc) thereby not activating a position sensor, and its in these cases that some people have reported in finding out that by lightly thumping (with hand) the bottom of the camcorder the fault can be corrected, or alternatively sometimes by pressing lightly on the cassette door. In other models contacts located at the inside top of the loading tray may just require a simple clean In saying all that though, an error code of E-04 in its simplest can be down purely to a dirty video head interrupting the data transfer to the logic circuitry, there in again as aforementioned in its "simplest" fashion! as many more expensive to repair reasons may be the cause.