Link to a watch repair article.
Watch repair article

Good read and yes 10 will be standard as we are using synthetic oils those days unless your ms breaks .

I am just beginning to mess about with watches, but have been working on clocks since about 1980.

I can vouch for everything that Mickey says and state that it all applies to clocks, too. You'd be surprised at how often you will be pressing out a brass pin that is a millimeter long, and the durned thing suddenly lets go and flies off into the great unknown. And I have seen more clocks with battered up screw heads than not.

Here's a prime example. How or why the underside of this hex head screw was all chewed up is completely beyond me. I can't imagine what the "repair person" was thinking or trying to accomplish.