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Examining the Escapement (Before taking the watch apart)

Before taking the watch apart, the several actions should be examined and any fault noted. See that the balance is true, both in the round and flat; also notice the action of the balance spring and that it develops uniformly. Try the various endshakes, which should be only the amount necessary for freedom. If the sideshake at the pivots is more than what is necessary for freedom, a new jewel should be fitted or a new part made, depending upon which is at fault. Stop the balance and notice the location of the impulse and unlocking pallets. When at rest the unlocking pallet should stand near the unlocking spring with the impulse pallet near the tooth of the escape wheel, which will deliver the next succeeding impulse, but the position of none of them should be changed until the watch has been tested for isochronism and in the various positions, since they may have been thus placed to complete some of the adjustments. Notice the amount the unlocking pallet carries the detent beyond what is necessary to unlock the tooth and at the same time see that the incoming tooth strikes safely upon the impulse pallet; also the distance the pallet is forward of the tooth at the time the tooth falls upon the pallet. The extent of the drop should not exceed five degrees, and may sometimes be slightly less. The distance between the edge of the impulse roller and the two escape teeth immediately adjoining it, that is, the tooth which has just given the impulse and the one which will immediately follow it, should be just sufficient to leave the parts free and should be equally divided on each tooth. If the lights, as they are called, are not equal, it shows that the position of the locking stone is not correct and which way it should be moved to correct the fault. Excessive side shake at the pivots, especially at the balance, might cause the inequality above referred to when held in certain positions. The escape wheel must be true in the flat, noticing that none of the teeth are faulty. The heights of the rollers should be so as to engage the escape teeth and the unlocking spring. The amount of lock of the tooth upon the locking pallet should be as small as possible, leaving a sufficient margin for safety. No workman who is not thoroughly acquainted with this escapement should attempt to repair it, for, since none except a first-rate workman could expect to make one which would give satisfactory results, so, none but a workman of equal skill can expect to repair it without leaving it in an imperfect condition.