Thank you! Well done and very descriptive. In looking at my Brunton (~early 1970's) there is no snap ring but there is a seal ring around the glass. Fortunately, there is no need to take it apart at this time. I cleaned the glass and mirror so we are ready to take it out into the field. I recently gave my grandson a pocket compass that he marveled over. Hopefully some day when he is mature enough he will get the Brunton with the staff thimble and ball and socket tripod head to enjoy.