here is a shot of a Hattori (left) next to Laco (right). No markings on the Hattori that indicate the cal. ...
OK - thanks for the pics! From what I see there, the Seiko/Hattori used was the 17j (lowest jewel count variant) Diashock version [Seiko experimented with several designs of anti-shock springs & Diashock was the one they finally settled on after a few other styles were implemented in production movements] of the "Marvel
" movement (also used in the Laurel, sort of a cost-reduced Marvel). Indeed, these movements from the '50s had no calibre identification markings [Marvel was introduced on "Time Memorial Day" - a "one time" holiday in Japan, June 10, 1956]. But, the shape of the plates, the presence of Diashock, the style of jeweling all point to it being that movement