Problema NTSC ZENITH 16Z8C50

[colortubeman]

Hello everyone, I apologize if the text is difficult to understand because it is filled with a translator.
I'm an Italian collector of old color TV (colortubemania in youtube) and now I'm trying to fix the chassis ZENITH 16Z8C50.
Unfortunately, the TV has been tampered with and many components have been removed on the decoder to match the NTSC color system PAL Italian with an external adapter that I did not.
Now, as the video source in Europe you can remodel in NTSC I would reconstruct the original.
Unfortunately the schematic I would not find that here in Italy if you can help.
Now I have a similar schematic to the frame 15V6C15 but definitely not the same because the NTSC does not work .
The TV was not used much and I think that the valves are in good condition.
The image changes color in the sides of the screen while it is ok in the middle
Can you help me find the schematic and see where the problem lies?
Thanks so much for any advice that I give.