I've done some troubleshooting.
I did a voltage check on the 3 tubes V15 a 6SN7GT Horizontal AFC and Osc., the 6BQ6GT Horizontal Output, and the 6W4GT Damper tube. Here are my findings. 2nd values are my readings:
6SN7GT
1 -2.8v -25v I thinks SAMS made a mistake here. Riders shows -40v.
2 100v 105v
3 -22v -16v
4 -60v -59v
5 235v 190v
6BQ6GT
4 140v 128v
5 -8.6v -8.6v
6 220v 190v
8 5.6v 6.3v
6W4GT
3 320v 250v
4 320v 250v
5 220v 190v
6 310v 255v
The voltages don't look too bad. Most are a little low.
I did hook up my scope to the grid (pin 5) on the 6BQ6GT tube and here is what I got:
I then checked point "C" on L19 per Sams on adjusting the Horizontal Sweep Circuits. This is what I got after I adjusted "B3" on L19.
I don't know what the frequency was but the time dial was set 10us.
Here is a picture of the schematic showing the area:
I also ohmed out the fly-back and it checked out pretty reasonable.
EDIT! I remembered that I can hook up my frequency counter to my O'scope and I then adjusted the Horizontal Frequency "B2" to get 15,734 cps.
Another EDIT! I added the voltage on the 6BQ6GT Pin 8.