Sounds like cracked solder joints on the monitor boards...
Discharge the high voltage on the monitor, unplug all the connectors (high voltage leads, DAG ground, AC power, RGB/H/V cables, yoke connector, degaussing coil, and any other connector.) and remove the boards from the cabinet - even the one on the back of the picture tube. Take 'em outside & blow 'em off with compressed air or a can of "air" then take 'em back inside and look at the solder joints for cracks.
If you aren't sure how to discharge the picture tube just take a long flat bladed screwdriver and a wire with aligator clips at both ends. Clip one to the monitor chassis - any metal point - and the other to the screwdriver. Slide the screwdriver under the big rubber cap on the side of the tube. You may hear a little crackle or snap sound. That is the high voltage discharging. Wait 5 minutes and repeat. Then you can slide the screwdriver up under there and use it to push the little metal clips together so you can remove that high voltage wire.
If the yoke connector is hard to remove you may have to rock it back & forth longways to remove it. The little board on the back of the picture tube may have some type of silcone holding it on. You'll need a razor knife to cut through it so you can remove the board.
You'll typically find that all the connectors and the flyback transformer (high voltage transformer) will have cracked solder joints. Fix those and that should take care of the flickering.
Use a flashlight and look around the rest of the board for any cracked solder joints. They'll look like they have a "ring" surrounding the pin that is sticking through the board.
It's not hard to do this kind of stuff. Just make sure you put the wires back correctly. Most of them will have a mark or an offset pin for pin 1.
Good luck!
RJ
