Mike:
To me, it looks like an electrolytic capacitor is bad. I had a 19" CTX
last week that had a simular problem. It turned out to be a 1000Uf/16V
capacitor had gone done in value to about 50Uf.
I would start by checking the caps in the secondary of the power supply
first. Then check the ones in the horizontal/vertical sweep section.
And finally check those on the CRT neck board.
An ESR meter comes in handy here to check the caps in circuit.
John