BVMD14H5U - Single Dark Horizontal Line

[Decaffeinator]

I've just recently bought a Sony BVM with about 5200 hours on it. There's a single dark horizontal line about 3/4ths of the screen from the top. It persists on restarting the system, as well as when switching display cards. It was a little difficult to capture, it's a bit more visible in reality:



Full Size: http://i.imgur.com/hToqU4s.jpg
I used the maintenance menu's FLAT FIELD function for this image, but it is also visible when displaying from other sources.



Any thoughts? I'd appreciate any input.

[Fudoh]

tension wire to keep the aperture grill in place. Normal for all Trinitrons.

[Decaffeinator]

tension wire to keep the aperture grill in place. Normal for all Trinitrons.

Well I learned something new today. I think you're right, thanks!