On quartz-electronic watches, the crown sets the hands only, but the crown on a Seiko mechanical watch both winds the mainspring and sets the hands. In time, the crown may wear, lose its knurling and become difficult to grip. A watch repairman performs this work as a routine service, but the mechanically inclined Seiko watch owner can successfully remove the crown from the winding stem of the watch with a few speciality tools in 20 minutes.
Inspect the watch to determine the method required to remove the case back. If there are a series of small slots around the perimeter of the case back, you will have to unscrew it.
Adjust the points of the case back wrench for a snug fit across the slots. Remove the back by turning the wrench counter-clockwise. If there is a slot in the area where the case back meets the case, it is snapped in place and can be removed with a case knife.
Insert the blade of the case knife into the slot between the case and the case back. Pry the back from the case with a firm, smooth motion. Take care not to damage the thin case back O-ring gasket.
Place the watch face down on a soft cloth. This will protect the crystal from being scratched or otherwise damaged.
Locate the stem release lever. Wear a magnifying eye loupe or use a lamp with a magnifying lens to perform this step. There will be a small indent on the side of the lever which holds the stem in place.
Depress the indent on the stem release lever gently with a plastic toothpick or watchmaker's tweezers. Remove the crown and stem from the watch while depressing the lever.
Insert the watch stem into the jaws of the pin vice and tighten securely.
Position the crown over a lighted candle for a few seconds. Do not allow the flame to come in direct contact with crown. The heat from the flame will warm any adhesive that may have been used when the crown was mounted on the stem.
Remove the crown from the heat. Immediately turn it in a counter-clockwise direction with small pliers to unscrew it from the stem.
If the watch has a bracelet as opposed to a strap, it may need to be removed to provide room to work. If so, use a spring bar tool to remove the bracelet.
Do not use wooden toothpicks to depress the stem release lever. Small pieces of wood may fall into the movement creating stoppages. Work carefully when removing the case back with a case knife to avoid scratches.