I have a Toshiba model CX35F70 that is about 10 years old. Recently when the picture contains light coloured elements there is a noticeable buzz coming from the TV, escalating in volume as the picture gets whiter. As this is winter in the snow belt of Canada I am getting lots of pictures featuring white. It is greatly diminished or absent with darker scenes. It persists even if the volume is reduced to minimum or muted. I have been searching the 'net to determine what the problem may be to no avail. One technician suggested it may be a loose shadow mask that vibrates when there is a high energy picture like a white background. I want to know what may be happening so I can determine my next course of action. If it is a tube replacement is there enough value left in the TV absent Colour Stream inputs or is it now time to look to replace this unit? Thank you for your assistance and guidance.