Yes, I was just assuming Tektronix called for a time mark generator as part of the horizontal cal procedures, not anything specific to the CRT adjustments. I took a quick look at the service manual and that seems to be the case.
BUT, let me take this opportunity to rant a little about Tektronix cal procedures. They usually call for specific pieces of equipment (usually their own brand, but not always), then tell you how to set the knobs on them and on the unit under test. So if you don't have the specific piece, you have to figure out what they are trying to do and then look around your lab for something equivalent. Not too bad usually. But, then Tektronix marches you through step by step without really telling you what's going on or why. I guess this is so an "untrained" person could theoretically do the cal. However, God forbid you miss or skip a step, because usually the support equipment and unit under test have been set a certain way 10 pages ago and then modified 50 times since. I've calibrated several dozen vintage Tektronix pieces over the years and it is always a chore.
Having said all this, after looking at the service manual, I would be astonished if you had all the necessary equipment. Even if you did, I would be astonished if you could get through the cal procedure without making a mistake.
Rant completed.