Seeking help to identify the maker of this movement & approximate date of make—simply signed “Gruen”, although I’ve not seen another Gruen quite like it. Winding mechanism looks like some LeCoultre movements I’ve seen, but looking for a more experienced eye. 11.25L, pin set at 1 o’clock position. Open face configuration. Back of dial hand marked “S5”. Dial side of movement has small stamped 6 digit sn, large stamped 5 digit sn, and two tiny hand marked #s (“10” or “01”) near pin. Seems to be a mark between the bridges near the balance wheel, but cannot clearly ID it or get a clear pic. Thanks!