Response from Jonathan: Rico,

Sometimes light black vertical lines can be caused by bad caps on your monitor chassis. You might try Installing A Cap Kit to see if it solves the issue. If not, it could be something related to a sync problem. You might try checking the sync wire that runs from your board to your monitor chassis to see if it’s damaged or disconnected. You might also touch up the solder on the back of the sync pin on your monitor chassis where the wire connects while you are checking the sync wire itself. Hope that helps.