OK, yes that is a pin set, if you look at the top of the picture in the gap between train and barrel bridges you can see the extension to the steel rocker bar (see photo below). You might also notice that for the missing balance cock there are two holes for pins set on opposite sides of the screw hole. I'd say the chances are high that this movement was made by Meyer & Studeli.
Now that was the easy part Getting a spare is not going to be so easy. This is a movement that I collect when I see them, just to build a stock of spare parts.
If you take the dial off and compare yours to the above photo we can be a lot more certain that yours is indeed made by M&S.