There were 12 M-models and one of them was the M 59-2 in 1964. As I understand it, M-series watches were available from 1961 through 1967 but I've only seen a listing for them in 1964.
The M 59-2 came in a two-piece case with a 10K RGP bezel and a stainless steel back. The dial is embossed with yellow numerals and markers. Tucked inside is a 17 jewel Swiss made Hamilton 686 movement.
I recently picked up an M 59-2 and it arrived in nice shape. The bracelet on it isn't original and it looks like it's period correct. In fact it looks a lot like the bracelet for the Electric Nautilus 400, except the ends would need to be different.
Cases with stainless backs can sometimes be one-piece designs and permanently bonded to the bezel. You'll sometimes see gouge marks were people have tried to open them in the past.
Close observation of the sides of the watch reveals a small gap - so this is a two-piece design and will snap apart.
The original dial is in excellent shape - which is good to see because it has a radial finish and is a challenge to get redone to look original.
I like the 686 movement. It's a clean, simple design and it has an adjustable balance cock so you can really fine tune the performance. I think it's interesting that Hamilton never produced an adjustable balance design like this. A lot of people turn up their noses at the Swiss grades but when you really get down to it, the Swiss grades introduced a lot of Hamilton's innovations... automatic movements, calendar movements, shock jewels, etc.
The 686 is easy to take apart and fairly easy to put back together. The train bridge holds all four wheels - so that can be the trickiest part, getting all four pivots to line up at the same time.
The movement is back to running - the motion looks good so it's off to the timer to find out for sure.
Well, something inside is making some extra noise so I'll have to remove the balance and re-clean the hairspring. It doesn't take much to make noise like this.
Well, the noise is gone now so it's time to adjust the beat rate and beat error.
How's that for performance? 3 seconds fast per day and a beat error of close to zero. I wish the US-made grades were this easy to adjust.
I decided to reinstall the bracelet that came with the watch... it looks good and since it doesn't go with any other Hamilton model I might as well put it to use. I was even able to polish the crystal that was on the watch so all this project really needed was a trip to the spa to run as nice as it looks.