E-O4 is an indication that there is a problem of data transfer between the video drum and its associated circuitry and can appear for something as simple as a dirty video head, however if this does not apply then the head itself could be defective or the ribbon cable that connects it. I would try cleaning the video head as a first measure as well as testing out the camcorder with another cassette, although it has to be said that sometimes in cases of a heavily contaminated head only "carefully carried out" wet cleaning can make a difference, info on this supplied if necessary.