Zenith 19EC45 Vertical Problem?

[jblmar]

Hi gang,
I have a Zenith 19EC45 with what appears to be a vertical problem. The picture is as bright and sharp as usual but the top and bottom of the picture is black. When the set is first turned on the bottom 3 to 4 inches and the top 1" or so are black. As the set warms up for a few minutes the area shrinks to
to around 1 to 2". A thermal intermittent problem would be the opposite. I suspect either the driver transistor which is commom to both the top and bottom screen transistors as well as the bias diode for the output transistors. I'll check the vertical module over the weekend. The problem is on all channels with or without the antenna connected.
Anyone have experience with this chassis?

Ron