To reinstall a top bearing plate, place this spool over the plate then gently tap with a rawhide mallet. Make sure the bearing plate is level and not tilted to one side.
• Unscrew the valve cap
• Remove the string by unscrewing the larger screw and loosening the smaller screws. If you are fixing multiple valves, label each screw and be careful to return them to their original spot. Maybe take a photo of the string before you untie it for ease in re-tying.
• While loose, the lever arm can swing around and scratch or dent the inner bell curve. Always hold it in place or protect the bell with your hand when moving the horn.
• Remove the rotor and stop arm by inserting the notched end of the metal bar into the back side of the rotor and tapping on it gently with the rawhide mallet
• Clean rotor and casing with brake cleaner, if available, or at least wipe down with a paper towel
• Thoroughly rinse rotor and bearing plate with lukewarm water and let air dry
• Cover rotor with light rotor oil and bottom bearing with light bearing and linkage oil
• Place rotor back into casing. Spin it around to distribute the oil.
• Cover top bearing with light bearing and linkage oil
• Line the witness mark on the bearing plate up precisely with mark on the rotor then reinstall it by placing wooden spool hole over the circle on the bearing plate and tapping in a circle around the top of the wooden spool with the rawhide mallet. Make sure the top bearing is not tilted to one side but lies perfectly flat.
• Spin the bottom bearing of the rotor and make sure it rotates smoothly in a circle but does not jiggle in and out of the casing
• Screw on the stop arm with the large screw
• Restring the lever
• Replace the valve cap
• If the lever does not line up with the other levers, loosen the small screw on the stop arm and tug lightly on the string and lever to reposition. Then re-tighten the screw and check lever alignment.