Removing a Snap-On Case Back
Remove the snap-on case back by inserting a
thin-bladed knife into a notch located between the case back and the frame. Rotate the blade to lever the case back away from the frame. This is usually an easy procedure. Still, observe these precautions:
• Use a lifting motion with your knife blade when prying off the case back. And don't brace your knife on one of the case lugs, which could break.
• Don't allow the knife blade to slide under the case back and into the watch movement inside.
• Be sure your knife blade is firmly in the notch before prying. Otherwise, the blade will skip off the edge of the case back and gouge it.
• If you can't get a good grip on the back with your knife blade, quit! Refer the problem to a professional watchmaker.
• Specially designed snap-on case back opening systems eliminate many of these problems. Most major watch brands offer their own systems, or you can contact your watch supply centre.
Removing a Screw-On Case Back
Remove the screw-on case back using a wrench, either hand-held or benchmounted. A few precautions:
• The jaws of the
case wrench must line up with the notches in the case back. Apply firm downward pressure to the wrench as you unscrew the back. Without enough pressure, the wrench is likely to slip and gouge the back of the watch – and maybe your hand.
• Many screw-on case backs are so tight you'll need to hold the watch in a special case vice when using a hand-held wrench. (Case vices are available through any major watch supply source.) Your hand may be strong enough to hold the case, but the torque applied while unscrewing such a tight case back will cause the watch to twist in your hand and can break the watch band where it attaches to the case.
• Using a bench-mounted screw-on case opening system will eliminate these problems.
Replace the Case Back
Even after you clean the area with a brush, a ring of contamination may remain around the case opening. Wipe this away with a cloth or a sharpened pegwood stick. Keep the case opening perpendicular to the bench top and rotate it so the contamination falls away from the case, not into it.
When replacing case backs, carefully remove the case back gasket, brush the edges and lubricate the gasket with a silicon sealant. This assumes the gasket is not stiff, cracked or broken.
If the gasket is damaged, tell your customer it would be best for your store's watchmaker to replace it. Snap-on case backs can often be replaced with finger pressure, but keep fingers off the crystal – it can break under pressure. Align the stem notch in the back with the stem or the back will not go on properly.
If finger pressure won't snap the back on, use a case or crystal
press. Align the watch in the press so there's no pressure on the crystal. If you don't have a press, speak with your store manager. This operation is critical, and a good press will avoid repair delays. If the case won't go on, you'll need to send it to a watchmaker.
With the screw-on backs, it's important to tighten the case back about half a turn after you feel it tug on the gasket. Too much tightening will cause the gasket to stretch and curl, reducing its effectiveness.
