Looks like a D16 chassis table model set I rescued a while back. I have been able to get color back and better convergence since I last updated that thread, but it still could use some work (dead sound and color acuracy issues). If I can get life out of that heap yours should be easy to get perfect.
http://videokarma.org/showthread.php?t=258006
By HO Tube are you talking output or oscillator? The output should not have an effect on the hold...It it the oscillator that is responsible for keeping the horizontal in synch. The horizontal phasing diodes mentioned earlier are a possible cause of horizontal issues.
I have a paper copy of the sam's photofact manual for the D16 chassis that I can give you excerpts of if that will help.
One thing to keep in mind is that if you can get the set to synch to a VHS source and there is horizontal waviness (flag waving) in the image (especially at the top) it is not the sets fault so much as it is the fault of the lousy synch VCRs tend to output. That set was designed before VCRs were common in homes and as a result were not designed to compensate for the lousy synch VCRs produce like newer CRT sets were.
There is a way to fix flag waving...Pass the VCR output through a TBC (Time Base Corrector) and then into your TV. There are a variety of TBCs and devices with TBCs built in. I've found that some DVD RECORDERS have decent enough TBCs built in to stop flag waving...