CTC 38 still trouble shooting

[damen]

I am still working on the CTC 38, It works good for the most part but on some scenes with white letters and a dark back ground or something with high contrasrt will cause a slight shadow across the screen most of the time the picture looks normal but turning up the contrast or AGC makes it worse it's not a smere like a week crt it checks about 80 on all three guns and its not the reception. Sometimes you can see that the top of the screen is just a tiny bit brighter than the lower part of the screen you can't see this on a full screen image but if it is a wide screen image with the black bars on top and bottom the top is just a little brighter. I have tried different tubes checked the video transister and in that area and grounding threw out and for loose conections even thow it's not Intermittent but no luck. Anyone have any ideas what may cause this or where to look?

[freakaftr8]

I have seen this on one of my CTC-17's Im not sure what it is but some kind of overload..