1965 Zenith Linearity Problem

[compucat]

My now ten year ago restored Zenith 25MC33 roundie has developed poor vertical linearity. Everything is stretched when the vertical fills out the screen. If I adjust it for correct circles, the picture has to be pulled in about two inches from the top and bottom. This has happened rather suddenly. Could this be bad capacitors in the vertical circuit? I have never replaced the couplates if that might have an effect on linearity. The picture below does not necessarily show what is going on but just so you can see which set I have. I think it could benefit from some service as the focus is slow to come up much of the time, there is some horizontal jitter and occasional loss of horizontal hold. There is some flashing of green in the raster until the set has been on for about fifteen minutes or so. After restoration the performance was excellent and consistent for a long time. I guess it is time for a good thorough servicing. I suspect some tubes are weak but my tube tester does not list most of them. I guess the tube tester is older than the set.

P.S. I do not know why the picture is rotated 90 degrees. I am doing this from my iPad Pro.