VECTOR: Cinematronics Monitor Troubleshooting

Just picked up a pretty decent Star Castle. Game plays blind.

Deflection chatter heard, hv fine. Screen is dark until I turn up brightness
and the entire screen gets lighter, no vectors being drawn. 

When the power is turned on, the heater glows brightly, then dims. Sound 
like a bad tube? My first reaction was start on the intensity circuit, but
seeing the heater glow brightly and then dim seemed strange.

Thanks, 

Jim 
http://www.arcaderehab.com