My Sony KV-21LS30U CRT set has recently begun displaying white flashes on screen. The flashes appear at random positions all across the set and occur at around three per hour of viewing. I have had the TV for a few years now and the problem began around six months ago when the flashes were pin-prick sized. Now they are quite large and eliptical in shape. Has anyone else experienced this effect (not necessarily on a sony set), can it be fixed? Thanks.