Update on the Type 547.
After much research I discovered that my low S/N scope was wired as shown in the first schematic. D1109 is a 105V zener and vertical output transistors are RCA TA1938. I could not find any info on those transistors but I stopped searching after figuring out how to upgrade the vertical amplifier. Q1109 is a 2N3441.
Since the TA1938 transistors were unobtainium did the upgrade as shown in this schematic. Q1109 remains a 2N3441. D1109 changes from a 105V zener to a 110V zener. Silicon diode D1114 is added. The vertical output transistors (Q1114 and Q1134) are now RCA 2N3119 which are much easier to find but still not common.
Pix of 105V zener before removal.
The new 110V zener and silicon diode bodged in.
New 2N3119 output transistors installed.
And the results. It appears I finally after months of work have all the gremlins out of this scope. The trace is somewhat fuzzy because I'm still on the external +100V supply and it's noisy as hell since it's a switcher. But I'm not going to go back on the internal +100V until I'm totally convinced this bastard is fixed.
At last.