smear

[radio nut]

My latest project is a RCA 14-s-7052 (sam's set354 folder 16). The picture is ok but has smear, both white to black and black to white.What causes this ? As always the set has nos tubes that have been checked and rechecked and paper caps and electro's have been replaced. The B+ is within 5 volts of the diagram and the voltages around the video IF and vid-output tubes look close enough. The contrast control can get rid of the smear but then the pic is more gray than black and white. Not knowing if it is a mistake I am trying to set the contrast the same way as my other tv, so I am not sure if this set is not capable of a strong contrast. Any Ideas?