Vintage chronographs are a hot commodity right now and have been for some time, and it’s not looking like that market will be slowing any time soon. With prices soaring for well-known Swiss brands, some consumers and collectors are looking further afield to satisfy their desires. The vintage Seiko market has been growing steadily over the years as collectors realize the enormous value from particular models. The most popular of these would have to be the original 6139 series of chronographs. 
The Seiko 6139 was produced in 1969, a big year for the automatic chronograph, as that was the year the famous Zenith El Primero was introduced, as well as the Heuer/Buren Caliber 11.  The 6139 was a single-register chronograph, displaying elapsed seconds and minutes, and it came in two variants: the 6139A and the later 6139B, which replaced the A. The watch under the microscope today is a Seiko 6139-7010. It features a ?military? dial, as it?s rumored this watch was a Japanese Defense Forces-issued piece. This particular variant is the 6139B caliber with a 21-jewel count. A 17-jewel variant also exists, but I?ll get into that later. This watch was purchased by a Canadian Seiko collector (@canadianwatchguy) who sent it to me for a full overhaul.
Now, these 6139s tend to be solid, reliable calibers, and this watch wasn’t running terribly, but it needed some general maintenance, the crystal was scratched, and the bezel had been rounded due to over-polishing. With a NOS (...