[Heath] SB-610 display

[Steve]

I seek advice regarding the display on my SB-610 monitor scope.

The left side of the displayed trace looks to be "normal." Beginning 
about the center of the screen and onward to the right, the trace 
contains is segmented into distinct, closely spaced vertical lines. I 
have just recently noticed the vertical lines, not sure how long they've 
been there.

Any ideas as to why the right side of the display is composed of 
vertical lines while the left side is not?

Thanks.

Steve K8JQ