wonder of wonders! Just had to follow-up on this, as I did solve the trouble. I had moved the base station to my portable phones to the right-hand side of the monitor, and yesterday when I thought about radio interference, I moved the station a few inches to the left and the trouble stopped. When I moved it back, the bands of scrolling scrammbled video reappeared. So, it was a good example of the age-old problem of too many objects on the same wavelength.