Thanks for the excellent description Raymond!
Two things: I checked my working scope, and the range is precisely 10.00 turns. Mine starts at 0.25(5) (5 is estimated as midway between the 5 and 6 tick marks), and ends at 0.25(5).
There is a calibration procedure in the service manual:?. I don't fully understand the procedure yet - I don't have a Time Mark Generator nor experience with one. But as Raymond described, it seems to be differential, not absolute. And I don't see (yet) an initial setting calibration. See page 5-57, item 77 through 79.
Besides twirling knobs to check functionality, I haven't had the chance to really dig back into the B timing. I'm only going off my memory of 35 years ago. So thanks again for the concise description Raymond.
Dave
Dave Peterson