"The capacitor didn't look too bad."
When it comes to Electrolytic capacitors, ANY DEFECT no matter how small is a DEFECT and you change it. Also you change them after 5 years since they are now past their life span. I know folk are new to this area so be gentle with them and research, go get data sheets and show them the curves.
I am attempting to see if an HP 1702 can be salvaged. The monitor flickers even before the PC is turned on, and continues to flicker after the operating system has loaded.
I opened it up. Checked the capacitors on the main board and the power supply. They look good, but could they still be the cause, or is something else more likely?