RCA CT-100 No raster
 

My RCA CT-100 powers up and delivers good sound. The 15GP crt filaments light up and all tubes seem to light up w/o any obvious gaseous blue color. Trying not to pull the heavy chassis and hopefully something obvious that can be addressed top side with the cabinet top lid removed. Just a shot in the dark I know. Any suggestions?

Since you have not specifically given much details other than you have sound, and all tubes seem to be lit OK, but not much other than that is known, not much to go on.
So starting with the basics, is there HV, or not, 19-20kv?
If present, then each element on the 15GP22 should be checked to see if they are within their normal ranges, this should give you some idea where to start is one or more is way off target.

I see that it has a ballast tube, could one section of it have failed and you still have IF/Sound? How often do the fail?

Has it worked recently?

First, remove both horizontal output and damper tubes, clean pins, and lightly coat with Deoxit, plug them back in and recheck.

If that does not help, unplug CRT socket and check all the voltages except
focus and convergence ... be VERY careful not to get anything close to those two places.

IF they are OK, if you have a good HV probe (good to 20 kV) check convergence and focus voltages. Convergence is derived from the main
19.5 kV HV supply so it checks that.

Beyond those checks it gets more equipment dependant.

I've had no raster twice: once was a filament pin that was not contacting, the other was a damper tube pin not contacting.

Thanks for the tips.

I had a 21CT55 with a bad fbt and other problems ca 60 years ago that iirc the chasselis could be accessed from underneath the assembled set. Is this one similar?
You do have operational FBT function?