The mainspring presents a slight difficulty in that original replacements are almost impossible to source.
The choice then is limited to recycling a spring from a junk 6139; finding a regular 61 series mainspring (i.e.
We’ll see to what extent that is born out as we work our way through this current project.
The hour, minute and seconds hand come off in conventional fashion, but the minute register hand sits so close to the dial surface that the most prudent way to remove it is to gently lever up the dial from the movement until the hand pops off.
With the day disk and date ring removed, the calendar side looks essentially the same as the 6106, barring the substitution of a couple of plastic parts.
The mainspring is very clearly no longer a perfect spiral but has been badly distorted both in and out of plane.
You can see the bends in the left hand photo and may be able to appreciate that the spring is no longer flat either, in the photo on the right.
Nevertheless, in common with many of the mainstream Seiko movements of the time, it has proved to be remarkably robust yet it is this robustness that can be blamed for some of the difficulties these movements present when reviving them.
That may sound like an odd statement, but longevity, even in robust designs, results in wear and with the youngest examples now at least 40 years old, most of these watches will have had multiple services, not all of which executed by competent watchmakers.In other news: in a nationwide referendum, the UK voted to remain a member of the European Community following the election of Harold Wilson in October of the previous year; the UK became an oil-producing nation for the first time; Jaws premiered in the UK, becoming the highest grossing film in history and Angelina Jolie Voight was born.The 1970’s was an era of extremes in fashion and, yes, taste, with voluminous glittery bell-bottoms, platform boots, tartan waistcoats and ridiculous top hats battling it out with avocado bathroom suites and mustard paint jobs on the automotive output of that lumbering, strike ridden monolith that was British Leyland.Over to the train side of the movement, and dismantling proceeds without drama, and reveals no unpleasant surprises other than a very decent degree of tarnishing of some parts, most notably the centre wheel bridge.However, in opening up the barrel to inspect the mainspring, we encounter the first sign that someone has been here before.those fitted to the 6119, 6106, 6105 etc) and hoping that they deliver the same power as the correct 6139 part, or trying a Generale Ressorts replacement of the correct dimensions. Assembly follows in reverse order to disassembly, starting with the setting mechanism, then over to the centre wheel and its bridge, the barrel, centre chrono wheel and third wheel followed by the barrel and train wheel bridge.