I've had this watch for more than 20 years and love it; of course at 32 x 23 mm it's probably regarded as ""too small". The mainspring has just failed so I need to pull it apart for the first time. Not long after I first acquired it I did a bit of research and if I recall correctly saw an identical movement in a watch listed as being from 1938. Dr. Ranfft's site doesn't have anything similar so I'm wondering if any Glashutte enthusiasts out there recognise it? A spec for the main-spring would be useful if not essential. Postscript OK. After removing the dial I find that it's an UROFA 58 and indeed is listed in Ranfft as 1934-38. Which makes it all the more remarkable that it's in such wonderful condition.