Although the automatic movement loses about 3 minutes by the end of its approximate 37 hour power reserve period and the date wheel rolls over as it should the crown/stem is temperamental. While the crown/stem connection is solid it’s difficult to pull the crown out to set the time. And when the crown is pushed back in and then immediately wound the minute/hour hands want to move. When this happens I’ve noticed that by turning the crown counterclockwise several times before applying inward pressure while turning it clockwise the hands don’t tend to move and the crown can be wound smoothly. Occasionally it’ll temporarily sound like crunching before the crown begins to wind without issue. Given this issue with the crown/stem and considering the movement’s unknown service history a complete overhaul is required. This seldom seen vintage 1970’s Tiara Aqua-Guard 660 diver, which came from the estate of its original owner, has a black “SWISS MADE” signed dial that shows wear and the lume emits a quick burst glow after being exposed to bright light. The black bezel, which shows wear and rotates bidirectionally with an appropriate amount of tension, presents nicely. The chrome-plated case shows considerable wear and brassing. The outer edge of the case back is stamped “MADE IN SWITZERLAND AUTOMATIC AQUA-GUARD SUPER-WATERPROOF 45457″ with “PRESSURE-TESTED UNDER 20 ATMOSPHERES (660 FEET)” stamped along the inner edge and “INCABLOC” stamped in the center. The crystal needs to be replaced. While I normally show pictures of the movements of watches I put up for sale I’m unable to remove the case back on this watch. The automatic movement with semi-quickset date function runs strong, albeit slow, and the date wheel rolls over as it should. The semi-quickset date function works by manually rolling over a new date and then moving the hour hand repeatedly between the 20.5 and 24 hour marks until the desired date has been reached. However, while the crown/stem connection is solid it’s difficult to pull the crown out to set the time. After recently winding the non-screwdown crown 39 full revolutions the movement lost about 3 minutes by the end of its approximate 37 hour power reserve period. This watch measures approximately 35 mm excluding the crown, approximately 38 mm including the crown and approximately 20 mm between the lugs. Case thickness, measured from the bottom of the case back to the top of the bezel, is approximately 9 mm. Including the crystal thickness measures approximately 11 mm. A complete overhaul is required. As such there are no warranties, express or implied, attached with the sale of this watch. Vintage means old and while my personal belief is that old-school means better quality and workmanship, things can and do go wrong from time to time. For this watch that time is now. Any servicing costs going forward are your responsibility. And please study the 13 high magnification pictures carefully as they are part of the description and serve as an accurate representation of the condition of this watch.