Hello,
I have an older Trinitron computer monitor which has recently started
displaying one-pixel wide slanted pairs of blue and red lines. The
paired lines slant up, left to right, with the left end of one set
level with the right end of the next lower pair. The pairs are spaced
about 17mm apart. These lines are only visible on a dark (black)
screen, not on a white screen. The image on the screen is not
distorted.

Can anyone suggest an explaination for this? Is it repairable? Will
it get worse if not repaired?

Thanks,
Epi