Hello I've got a Panasonic TV model TX-29AS10F chasis EURO-4H with a color purity problem at both sides of top of the picture. Top left has a greenish tint and top right is yellowish, the rest is correct including top middle. That discoloration gets worse as nearer to the edge. This model is 100Hz and has a completely flat CRT front.
In the user settings it has a geomagnetic correction menu that lets the user rotate the picture slightly, the curious thing is that adjusting that also moves that purity defect. The right one can be eliminated completely this way but then the left one expands even more. The opposite is also true but the left one can't be corrected completely.
I wonder if you belive it is more probably a CRT mask defect, a moved or misaligned yoke or some missing/fallen magnets. I don't see anything wrong apparently in the yoke but before I start playing with small magnets around the tube or moving the yoke I ask for previous experiences.
Thank you.