Replacing the Wind Cups
Your Wind Instrument is designed to allow you to replace the wind cups if needed. The cups have a tiny magnet in the flange at the base for the wind speed sensor. Earlier models had a brass jewel bearing in the top, but miniature ball bearings are now used in the Wind Instrument RB™ and in the replacement wind cup assembly.
For removing the wind cups, do not remove or twist the nose cone, which is permanently attached. Just loosen  the black dome nut and  the brass set screw in the side of the black axle tube. Use a 2 mm (or 5/64″) Allen key for the brass set screw.
The nylon dome nut might be one of two sizes, and can be loosened with either a box-end wrench that is either 3/8″ (larger dome nut) or 8 mm (smaller dome nut). Remember to turn counter-clock wise to loosen, to avoid stripping the threads on the nut. The replacement is quick and simple, but if you do the repair yourself, SailTimer Inc. is not responsible for any damage that is caused.
The axle/wind cups assembly is a single unit that is press-fit into the black base. To remove the previous axle under the wind cups, just twist and pull it out (with pliers if needed, possibly wrapped in cardboard or rubber if you want to protect it).
Models using a jewel bearing had a 5 mm axle hole, but the new wind cups assembly has a 3 mm axle diameter. For that situation, a small white bushing is provided as an adapter. The white bushing is temporarily on a screw that you can hold while adding superglue around the outside of the bushing, and pressing it into the axle hole. Use a razor blade knife to pare down the edge of the bushing slightly if it won’t go into the hole. Once it is started in, remove the screw. Then tap the bushing in gently with a hammer (in your hand, not hammering down on the lower axle).
To press-fit the axle into the white bushing, check that it will fit. If the hole has become deformed, drill it out again with a 3 mm or 1/8″ bit. You may need to drill the hole about 1/8″ (3 mm) deeper, to keep the height and gap of the cups about the same with the new axle. Then put a drop of superglue around the end of the axle, and press-fit into the white bushing. Do not push the axle hard, to avoid damaging the bearings inside, or jamming the axle up into the cups; the axle should easily slide in, and will be held in place by the superglue.
The new axle assembly does not need the C-shaped retaining clip above the flange on the base of the cups. If your model has that, it can simply be left in place.
During reassembly, put some adhesive (e.g. a tiny drop of Marine Goop or superglue) on the threads under the dome nut to make sure that nothing comes unscrewed. Just a very tiny drop on the end of the threads will be sufficient. You may want to remove the dome nut in future, so you don’t want the dome nut permanently seized on the threads.
Then tighten the brass set screw (no glue needed there), and you’re done. Don’t worry, this will be clearer once you take it apart.