I remember those too. I used to adjust them and I seem to remember
blue and red coil forms. Take an alignment tool to the one marked disc
first. I don't remember if there was a top and bottom (primary and
secondary) to this coil. If so your tool will have to be able to slide
in to the top make that adjustment and then slide down to the bottom
section. Put a piece of tape on the tool like a flag. Note the position
of the flag before turning the tool so that you can return it to its
starting position if the adjustment does not change the audio. As I
recall just a slight twist was all it took to clear it up. Anything
related to "disc or 4.5mhz) is in the right neighborhood. Good luck,
Lenny Stein, Barlen Electronics.