Regarding replacing broken jewels, I also keep a full stock of these, turned (the setting) to match any make or style of watch; except, of course, Swiss watches, and for these I keep a large assortment of sizes, both of cock and foot and wheel jewels, and a full stock once procured, they last a long time and are a good investment, for with them you can meet any emergency.
In a Swiss watch, or any watch where the jewel is set into the plate, have some one of the devices for throwing up the burnished lip, and then select a jewel that just fills the space, and then with a smooth pointed punch, such as I described I used for closing up a pivot hole, I turn this lip back by sliding this round pointed punch around the outside, making it act as a burnish. Cap jewels I either treat in the same manner as the last, or cut away the setting, and insert them as they are inserted in most Swiss watches.
I have now taken up the more common repairs, and will close by hastily speaking of the more rare cases, and the adjustment of the hair spring, etc., etc. It is often the case that there is never end shake to the balance to make it absolutely safe when screwed into the case, and when this happens I take the point of a sharp graver and prick up a burr on the bridge, and never on the plate, as any unskilled workman does, for the under side of the bridge never being finished, you really mar nothing, and sometimes this raising of the cock (or bridge) becomes a necessity, to have it clear the rim of the balance, which, if raised, it will clear, and then by bending down the end of the cock at point where the jewel is, and thus regulate the end shake. I hardly know how to give directions how to proceed in adjusting hairsprings, when they are disarranged, but if I could see you, I could explain by example what I cannot well do in words. To commence, a hairspring, when there is no power applied to balance from the jewel pin, should be, when pinned, just as free from any twist or cramping as it would be if lying flat and free on a smooth piece of glass, before it has been pinned at either end, and when it is pinned in the watch (at stud and collet) it should be thus free. To bring it thus requires demonstration that cannot be made on paper, unless you could make diagrams, too numerous for this article.