I recently serviced this very nice Seiko 5126-6010 Sports from 1969 for a ClockSavant customer (fellow Instagram’er @chronopal.) The Seiko 5126 movement comes from the Seiko 5100 range of automatic movements produced in the Daini factory between 1969 and 1971 for the Japanese domestic market. Compared to many other Seiko models, the 5126 is relatively rare with fewer good examples and virtually no new old stock parts available. The 5126 is different from many other Seiko movements. It has more parts and complexity in its automatic and setting mechanisms. The automatic mechanism is a bit more “swiss” in design. The quickset mechanism has some unusual layered spring-driven sliding components that, in some ways, remind me more of a chronograph than a setting mechanism. When properly serviced the Seiko 5126 can provide excellent accuracy and amplitude and this watch is now running extremely well once again.