A 6¾ by 8 ligne movement on full plates rather than bridges. The manual argues the accuracy inherent in that design is what lets the escapement and gear train be fully interchangeable without selective fitting.
The Timex Model 23 is a 6¾″ x 8″ movement featuring the “V-conic” bearing system and rugged two plate design. Whereas most watches utilise bridges, Timex has constructed the Model 23 movement with full plates to take advantage of the accuracy inherent in this type of design. That accuracy, the manual says, insures complete interchangeability for the escapement and gear train without the need for selective fitting and adjustments which complicate the repair of most watches.
How far to strip it: To clean the Model 23 it is necessary to remove only the minute hand, dial and balance. The cleaning fluid removes contamination and also removes oil from the gear train, pivots and holes.
If further dismantling is required, removal of the movement plate will expose the gear train and associated parts. Reassembly should then start with the movement plate, exercising normal care to insure proper positioning of pivots in their respective holes.
Remove the dial by straightening the two tabs which clamp the dial to the movement.
Fig. 23.3 · Dial & Hands
2 · The Dial Tabs
The tab passes through the dial hole and is bent under the dial plate.
Fig. 23.3 · Dial Tab
3 · Removing the Crown and Stem
To remove the crown and stem, turn the set lever screw approximately 1¼ turns.
Fig. 23.4 · Crown & Stem
4 · The Set Lever Screw
The set lever screw seen from the movement side, and the set lever it releases.
Fig. 23.4 · Movement Side
5 · Removing the Balance
Two “V-conic” studs are used as bearings for the balance staff. The stud on the movement plate is driven into a screw so that fine endshake adjustment is possible.
6 · The Balance Assembly
Remove the hairspring wedge pin, being careful not to distort either the pin or the hairspring.
Rotate the balance slowly until the hairspring tail is free of the hairspring wedge pin bracket and the regulator.
Loosen the balance screw assembly counterclockwise using a suitable screwdriver, until the end of the balance staff is free of the “V-conic” bearing.
Carefully remove the balance assembly.
Caution: Apply only minimum downward pressure with the screwdriver. Excessive downward pressure could seriously damage the balance staff points.
Fig. 23.5 · Balance
7 · The V-Conic Bearing
Cross section through the dial plate, balance, movement plate, regulator and balance screw assembly.
Fig. 23.5 · V-Conic Bearing
Cleaning & Lubrication
Lubricant change, June 1974: Timex Service Bulletin No. 111 replaced the factory oil for this model. Moebius Synt-A-Lube oil is used instead of Elgin M56B oil. (It supersedes Bulletin No. 108.)
If a cleaning machine is used, place the movement in the basket with the dial plate down to insure proper drainage of the fluid from the mainspring barrel. It should be well swirled in the cleaning fluid, after which two sets of rinsing fluid should be used. The final cleaning fluid must be absolutely clean, and after cleaning the movement should be thoroughly dried.
If a cleaning machine is not available, the same procedure should be followed manually: re-insert the stem, grasp the movement firmly around the stem and shake it in the cleaning and rinsing fluids to insure the fluid passes through the entire mechanism.
The balance assembly should be cleaned separately in a small jar to prevent damage to the hairspring. Only standard watch cleaning solutions should be used.
Oiling: Re-oil using only high grade watch oils; Elgin M56b is used in factory assembly. The mainspring is permanently lubricated with a solid coating and should not be oiled. The “V-conic” bearings should be oiled no less than ¾ full before replacing the balance.
Reassembly
1 · Replacing the Balance
Replace the balance carefully into the movement by tilting the wheel and inserting first the movement side pivot, the hairspring side, then the dial side pivot into the “V-conic” bearing. Adjust the balance screw enough to hold the balance in place.
By rotating the balance, insert the hairspring into the regulator slot and hairspring wedge pin bracket. Before re-pinning the hairspring, make certain the impulse pin is within the slot on the fork.
Repin the hairspring making sure the wedge pin is straight and true, as any distortion to the pin could interfere with the normal “breathing” of the hairspring.
Caution: Adjust the endshake using only minimum downward pressure on the balance screw, as excessive pressure could damage the points of the balance staff.
Fig. 23.7 · Refitting
2 · The Hairspring in the Regulator
Inspect the hairspring to be certain it is properly adjusted. The hairspring should be positioned centrally within the regulator slot.
Fig. 23.7 · Regulator Slot
This guide is based on the original Timex factory service manual for the Model 23 movement.
