I have a panasonic television model #ct36G22. It is over 10 years old.

I am experiencing a black screen with a very thin picture line horizontally in the middle of the screen, going all the way across.

This is happening upon startup of the TV, after it has not been used for a while. There have been weeks at a time where it does not happen at all. After a period, the screen becomes normal. This takes anywhere from a few minutes to a half hour or more. During the black screen, the normal picture flashes off and on. The sound is okay.

Repair possible, or is it just too old.

It means you lost vertical deflection. Since it's intermittant, it could be thermal or a loose connection.

Remember in early 2009 the US switches to digital broadcasting. It might not be worth fixing.