NavList:

Hi Todd - the sextant I mentioned has an electronic averager and, yes, I've timed it and it runs for 120 seconds each time.  I have tested it by putting in a step altitude change at the 1 minute mark and the averager always gives me an average altitude of half of what I put in.  I generally start the two minutes at the top of of the minute at a precomputed time - I hack the watch just before going out so I do not expect any drift from UTC in the 20-30 minutes or so to complete the shot.

Good questions!

I also took a look at the index system.  It uses pushrods and I cannot detect any backlash in it.