I am sure that there is a problem somewhere on the RF deck, the contrast and the brightness tend to have the same effect on the picture.
The contrast alters vastly over a small amount of travel. it is near on impossible to obtain a normal picture. Scene changes when viewing a program can make the picture go from overbright to very dark.
When viewing the test card it is difficult to get either correct contrast or brightness over the whole screen. the picture focus is not to bad.
Mark