Another patient on the operating table: my Samsung CK4644 CGA monitor. Lots of shielding so I can't see much, but I was able to get to the front potentiometers (pulled them out, see lower right of the monitor); contact cleaner will be sprayed as these two are completely stuck and won't turn at all.
Brightness and contrast potentiometers now can turn, though still seem a little scratchy. Will be applying more contact cleaner.
After fiddling with the vertical hold pot, image is a bit less shaky (pot seems a bit scratchy too) - contact cleaner spray will be in order here as well as all easily accessible potentiometers. This is by far the easiest step and if it fixes most/all of the visible issues I'll be content.
Bits&Terminal Jeff