Just a SWAG regarding the smearing of fine detail in the pic.. since there's evidence of hacking in the video amp area, maybe someone has tried to hack in a DC restorer circuit. Maybe you could post the schematic of the vid amp area.
Need to determine first if the smearing is occuring 'downstream' of the video detector or
upstream of it. Always think of the vid detector as the "continental divide" when localizing any kind of smearing/ringing problem in the displayed image.