The "white stain(s)" can be removed.
In geometry menu try to adjust: V SIZE, V POSITION, V LIN, S CORRECTION and V ASPECT. I mentioned all these parameters because the "removal procedure" is related with vertical size/position of the screen (aparently those stains appear because the image is positioned "too down").
I really don`t know if those stains should appear even if the image is underscaned or positioned "too down". Also I don`t know how can you obtain - without a professional test pattern generator - a perfectly(H and V) centered image, so that you know how far from that you`ll be in the end. I said "how far" because after "the removal" your image will be a little overscaned and/or not vertically centered.
I use the following settings.
You may try them - of course on your own risk. In the red column are the actual settings and with black are the original ones. These setting should be modified in WIDE mode, because some of them are related with screen modes.
Anyone noticed the vertical picusion?
In normal viewing, this issue is noticeable only on channels where bottom horizontal scrolling text is present. I didn`t found a fix for this issue, yet. Probably only by adjusting the deflection yoke. If anyone has a service manual for this tv please let me know.