After taken the movement from its case, removing the hands, dial, minute cock, and bridge, try the escapement with some power on, and note any faults there. Next remove the cock and pallets - putting a peg between the escape-wheel arms to prevent it from running down - and carefully let down the spring. Here sometimes you will meet with a difficulty; if the spring has been set up too far, and the clock is fully wound up, it may not be possible to move the barrel arbor sufficiently to get the click out of the ratchet. In many old clocks there will be found a contrivance to meet this difficulty. It is simply a hole drilled at the bottom of, and between the great wheel teeth directly over the tail of the click; so that you can put a key on the fusee square and the point of a fine joint pusher through the hole, release the click, and allow the fusee to turn gently back until it is down. This is a great convenience sometimes. Having let down the spring, try all pivots for wide holes, and if it is a striking clock, do the same with the striking train, paying particular attention to the pallet-pinion front pivot to see if it is worn, and the rack depth made unsafe thereby - also seeing that none of the rack teeth are bent or broken.
Having noted the faults, if any, take the clock to pieces, and look over all the pivots, and note those that require repolishing, Finally, take out the barrel cover, and see to the condition of the springs - if exhausted or soft.
In most cases, some repairs will be required to the pallets, as these nearly always show signs of wear first; if they are not much cut, the marks can be polished out without much trouble - and for this purpose you will find that a small disc of corundum about 3 in. in diameter, mounted truly on an arbor, and run at a high speed in the lathe, will be of great assistance; finishing off with the iron or steel polisher and sharp red stuff. If you have to close the pallets to make the escape correct, see that the pallet arms are not left hard, or you may break them.
After making any alteration in the pallets, you will generally find it necessary to correct the depth; should it only require a slight alteration, probably it will be sufficient to knock out the steady-pins in the cock, and screw it on so that it can be shifted by the fingers until you have got the depth correct, then screw it tight and broach out the steady-pin holes, and fit new pins. Sometimes one meets with a pallet arbor that has been bent to correct the depth. This is a practice that cannot be too strongly condemned, as it throws an unequal pressure on the pivots, and causes them to cut rapidly. If much alteration in the depth is required, it may be necessary to put in a new back pallet hole; this can be made from a piece of hollow stopping broached out and turned true on an arbor, and to a length equal to the thickness of the plate. It is not safe to rely on the truth of this stopping, unless it is turned on an arbor first. The hole in the plate is now drawn in the direction required with the round file, and opened with a broach from the inside until the stopping enters about half way. Of course, in finishing broaching the hole, you will roughen the extremities to form rivets.
Drive the stopping in, and rivet it with a round-faced punch from the outside, reverse it, rest the stopping on the punch, and rivet the inside with the pane of the hammer; remove any excess of brass with the file, chamfer out the oil sink, and stone off any file marks; finally opening the hole for the pivot to the proper size. If you have a depth tool that will take in the escape wheel and pallets, it will be quicker to put them in the tool, fill up both holes with solid stoppings, and replant them; but few workmen have a large depth tool.
Very frequently you meet with a scape pinion that has become so badly cut or worn as to be useless, and you cannot always purchase a new one of the right size; in this case, it will be necessary to make it from the wire, which you can always obtain of every size at the tool shops. In sectoring the pinion wire to the wheel, bear in mind that it will become slightly smaller in filing up. Considerable practice is re-quired to make good-shaped pinions quickly and well. A piece of pinion wire of a slightly greater diameter than the pinion is to be when finished, is cut about 1/8 in. longer than required, and the position of the leaves or head is marked with 2 notches with a file. The leaved portion of the wire that is not required, is now carefully filed down on a filing block, taking care not to remove any of the arbor in so doing; a centre is then filed at each end true with the arbor, and these centres are turned true through a hole in a runner or centre in the throw. If this has been carefully done, the pinion will be nearly true; it is now set quite true, and the arbor and faces of the pinion are turned square and smooth. The pinion is now filed out true, using a hollow-edged bottoming file for the spaces, and a pinion-rounding file for the sides of the leaves.
In using the bottoming file, the pinion is rested in a gallows tool described, and held in the fingers for the leaves, when finishing, to keep them fiat.
The file marks are now taken out with fine emery and oil; the polishers used for this purpose are pieces of wainscot oak, about 1/4 in. thick, 5 in. broad, and 6 in. long, used endway of the grain. One end is planed to a V shape to go between the leaves, and the other is cut into grooves by rubbing it on the sharp edges of the pinion itself, which speedily cuts it into grooves to fit. The pinion is rested while polishing in a groove cut in a block of soft deal, which allows it to give to the hand, and keeps it flat. When the file marks are all out, the pinion is ready for hardening. Twist a piece of stout binding wire round it, and cover it with soap; heat it carefully in a clear fire, and quench it in a pail of water that has been stirred into a whirlpool by an assistant, taking care to dip it vertically. Having dried it, it is covered with tallow and held over a clear fire until the tallow catches fire; it is allowed to burn for a moment, and then blown out and permitted to cool. The leaves are now polished out with crocus and oil in the same way that they previously were with emery.