Dismantling and Reassembly

1 Remove the movement from the case (section A). Remove the dust-cap, then (as a precaution against accidental damage) the hands (section B).

2 Remove the blue screw which secures the cock (the bracket, usually decorated, which holds the balance in place - see fig. 1); then carefully remove the cock itself. There may be a small slot in the foot of the cock where it meets the edge of the plate; a small screwdriver or the tip of a blade can be introduced into this to lever the cock away. If there is no such slot, hold the cock with a finger on each side, or at each end, and gently pull it upward so that it comes up level. Never lever it from one side alone, since this presents a risk of bending the pivot of the balance. The balance itself should stay in place in the movement; if it shows any sign of coming away with the cock, hold it down with a fingernail.

3 The balance-spring (hairspring) is secured at the outer end by a tapered brass pin. If the hairspring is beneath the balance-wheel (the most common form), this pin passes through a brass stud riveted to the back-plate; sometimes, however, the spring is above the balance and is pinned to a polished steel arm whose outer end is screwed to the plate. In either case the procedure is the same: -

(a) Take a careful note of how far the outer end of the spring protrudes beyond the stud or arm; you will need to put it back in exactly the same position in due course. It is legitimate and time-honoured practice to make a scratch on the back-plate just under the end of the spring.

(b) If the watch is positioned with the pin nearer to you than the balance, the pin will usually withdraw to the right. Remove it by pulling on the outer (right-hand) end with tweezers if enough of it is showing to allow you to do this without disturbing the spring; otherwise you may have to push it out from the other end. Use tweezers with rounded ends if there is enough clearance, since these are less likely to lose their grip on the pin (which is very tiny) and squirt it across the room. In any event it is especially important to do this job on a clear surface, a tray with raised edges being best.

4 With the tweezers, gently pull the spring anti-clockwise near where it enters the stud or arm until it comes free.

5 Disengage the spring from between the two little upright pins on the regulator pointer.

6 Lift the balance clear. The safest way to do this is to use two fingernails or two pairs of tweezers, on opposite sides of the balance, so that it comes up level.

1 Remove the movement from the case (section A) and remove the hands (section B).

2 Remove the fusee-chain (section C). Note that if the set-up wheel is on the barrel-bridge there is no need to remove the dial.

3 Remove the set-up wheel from the end of the spring-barrel arbor.

4 Remove the two screws holding the barrel-bridge (figure 2) and lift it away.

5 Carefully lift the balance just far enough to allow the barrel to be lifted out of its bearing in the pillar plate and slid out from under the balance. NOTE: Occasionally the hairspring securing pin, or the free end of the spring itself, may extend far enough over the barrel to prevent its coming clear. In this event the hairspring must be removed (section F 3-6).

1 Remove the barrel from the movement (section G).

2 Prize out the snap-in cover by inserting a screwdriver blade in the small cut-out at its edge and carefully levering upward.

3 Grip the upper end of the steel arbor with a pair of tweezers and turn it anti-clockwise. This will draw the hook on its drum-shaped middle section out of the eye at the inner end of the spring. Lift the arbor clear and put it in a safe place.

4 Engage the screwdriver in the hairspring eye and use it to pull the inner end of the spring upwards until it can be gripped with the fingers.

5 Holding the barrel firmly in the left hand (or in a vice), continue to pull the hairspring out. It will ‘fight back’ to a surprising degree as you approach the outer coils, expanding to 3-4 times the width of the barrel. Normally the outer end will push itself clear of the barrel automatically; if not, disengage it by sliding it anti-clockwise. Lift the spring away and put it aside for checking against the new spring (if you are planning to fit another one).