This likely indicates that the mainspring needs to be replaced. After a day of remaining fully wound and not running the movement then began to run after the watch was moved in a variety of different positions. It remained running for the next 33 hours, losing several minutes with the date wheel rolling over automatically as it should.
Given the movement's inconsistency and considering its unknown service history a complete overhaul is needed. This seldom seen vintage Bercona Sport has a matte orange "T SWISS MADE T" signed. Dial that is in near pristine condition. The imperfections seen are primarily on the underbelly of the crystal. The lume, which remains fully intact and emits a quick-burst glow after being exposed to bright light, has aged gracefully to a perfectly matching toasted buttermilk hue. In my humble opinion the patina is the highlight of this watch as it presents beautifully.The black bezel, which rotates smoothly bidirectionally, looks good. The chrome-plated case shows moderate wear with no visible signs of brassing. The outer edge of the case back is stamped "STAINLESS STEEL BACK BASE METAL BEZEL AND INDICATOR SWISS MADE" with "TESTED TO 5 ATM" followed by "551" stamped in the center.
He crystal, which has significant dust/debris on its underbelly, should be replaced as there is a small, difficult to see crack near the 5 o'clock marker. While I normally show pictures of the movements of watches that I put up for sale I don't have a press tool to press the case back on so no movement pictures were taken.
The manual wind movement with quickset date function had until recently run strong and kept accurate time. The quickset date function works flawlessly by manually rolling over a new date and then moving the hour hand repeatedly between the 19.5 and 24 hour marks until the desired date has been reached. This watch measures approximately 36 mm excluding the crown, approximately 39 mm including the crown and approximately 19 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. This watch comes on a black/gray/orange NATO strap that complements the bezel and dial beautifully. Given the issues noted and considering the movement's unknown service history a complete overhaul is needed. 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 12 high magnification pictures carefully, which were taken in natural light and from various angles, as they are part of the description and serve as an accurate representation of the condition of this watch.
The item "Vintage Bercona Sport Diver Watch withOrange Dial, Red Date, Runs FOR PARTS/REPAIR" is in sale since Tuesday, July 21, 2020. This item is in the category "Jewelry & Watches\Watches, Parts & Accessories\Parts, Tools & Guides\Watches for Parts". The seller is "savethetreestoday" and is located in Issaquah, Washington. This item can be shipped to United States, Canada, United Kingdom, China, Mexico, Germany, Japan, France, Australia, Russian federation, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Greece, Portugal, Cyprus, Slovenia, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Austria, Bahamas, Israel, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, El salvador, Honduras, Jamaica, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Uruguay.