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    Astra Micrometer Dial Calibration
    From: William Sellar
    Date: 2011 Jul 21, 04:28 -0700
    I have been a lurker on this list for some time.  I live and travel full time on a sail boat (Currently in Nova Scotia, Cape Breton Island) and am trying to teach myself celestial navigation as I go.  (Have not gotten very far)
    I have an Astra IIIb and have been practicing the sextant adjustment steps.  I may have a problem with the micrometer.  When the micrometer is set to zero, the index mark is not zero.  The micrometer must be set at 20 to 25 to set the mark to zero.
    If this is adjustable, I have not been able to figure out how.  Is this normal and something that is accounted for as part of index error?  If this is not OK does anyone know how to adjust this on the Astra or do I need to have it serviced.  I have not been able to find this particular problem discussed in any of my many books.
    Thanks in advance for any advice.
    Bill S
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