I've got a Hitachi TN-78042 27" TV that was working just fine. Then a
couple of months ago I noticed that from a cold start the picture would be
great but would deteriorate as it warms up until all I see is snow. Audio
is fine. The time that it takes for the picture to become scrambled (using
tuner or other video inputs) varies from 10 minutes to a couple of hours
depending on how cold the TV is. I tried using cold spray on the individual
components to no avail. Any ideas on what I should look for ? Thanks.

James