Typical Nintendo Sanyo 20-EZ problems.. vertical scrunch (remember your monitor iin a DK s twisted 90 degrees counter clockwise as compared with a horizontal monitor/tv set, so vertical to the monitor is horizontal to your eyes) Therefore you adjusting horizontal on the monitor actually moves the screen up and down. You would want to adjust vertical size/position instead to get YOUR screen to move left/right.
I bet it's not really missing the stuff, its just all the print for the first 1" of screen is scrunched into the first few lines that are there.
A standard cap kit will fix this. There are 2 cap kits available. One has an extra 10 or so caps that may or may not need to be changed. If this is your only problem the standard kit will work, but it is a pain to remove the chassis from a sanyo monitor so you may as well replace all the caps at once and get 20 more years of life out of it.
The best/easiest place to order is
http://www.therealbobroberts.com the standard kit is $5 and the deluxe I think is $7. He does have a flat $6 for initial 2 pounds shipping per order, but perhaps you can find other stuff you need to throw in to make it work for you. I dont know what Zanen charges for shipping.