Years ago my large CRT monitor slowly started having problems. A quick internet search convinced me it was most likely solder joints on the circuit boards failing. Opened it up, shorted out the CRT tube to get rid of stored energy and looked at the boards under magnification and sure enough, there were many cracked joints. It didn't take long with a low wattage soldering iron to clean it up. The monitor lasted for years until it was replaced with a flat panel.