The squeal is probably the line output transistor failing or dry jointed, they can go 'leaky' in resistance just prior to failing completely, often this is accompanied by a black band down the right side of the picture. Line output transistor failure is very common on old Panasonic's. (Component reference no. Q551). Other causes of noises are less important ie. a vibrating coils, but a high pitch squeal sounds like Q551, and it will certainly squeal like a pig when it fails completely.
After 10 years you can expect some noticable reduction in the tube performance. Also, the 25" to 29" Panasonic's of that era do have a tendency to suffer a dead spot on the screen control situated (along with the focus control) on the line output transformer, reducing screen brightness. Re-adjustment of the screen control is generally enough to correct the picture. Replacement of the transformer would be expensive relative to the age of the set.
Cobweb, December 2004
