Check that AGC
 

Not just with a meter but a scope if you are having any kind of picture issues esp on keyed agc, from lack of sync to negative pic to tearing etc...

I just finished up an old Emerson with a keyed AGC, had all kinds of issues (per above) turned out to be the AGC had noise, I presume from the HV circuit not being decoupled) that was obvious on the scope, but not on a meter (dmm or vtvm).

I couple quick things I will do for now on.

1) If I have raster I will make a direct video feed a the grid fo the video amp, this will cut the trouble shooting down to before or after that point.

2) Check the AGC with a scope.