My 1980 H27 has the original Signet knotlog MK267a. It will not stay calibrated which I attribute to a dead lithium battery that holds the memory. I don't have a manual on the knotlog. I replaced the existing 3.6V battery and the knotlog was then 30Kts off and would not calibrate. Removing the new 3.6V battery, got it working as usual (without memory) Looking at the printed circuit board, it shows 6V at the battery location. Anyone out there have a manual with a schematic or experience with the Knotlog?