Wayne, same basic circuit any 630 has.
http://earlytelevision.org/pdf/rca-630ts-sams-54.pdf
Now that I think of it though, there might not be anything wrong with the oscillator at all. Could it be that the difference in tube size is enough to physically make something like this happen? I mean, the original CRT was a 23CP4 and I have the yoke wrapped around a 10SP4. Could the difference in sweep angles between them make this happen? I'm not sure, I would think the center of a tube is the same no matter what size it is.