A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bill Morris
Date: 2019 Dec 8, 18:35 -0800
Responses have rather drifted away from your original question about servicing. Does your "pattern 491 look anything like this one? https://sextantbook.com/2018/02/14/hughes-and-son-admiralty-pattern-micrometer
If so, I would be happy to guide you through servicing it by e-mail, or I could (modestly) recommend the book as a guide. I have sometimes servced/repaired sextants for others who are "all thumbs", for the cost of the return postage, but am not touting for custom...