From the Peter White website
Frequently, people decide that I’m stupid, (Who can blame them?) and that in fact the notchiness they feel while turning the axle by hand is due to the bearings being adjusted too tightly. This is not the case. There is no adjustment for the bearings! They are sealed cartridge bearings, and require no adjustment. Nor is adjustment even possible.
On the end of the axle opposite the electrical connectors of older SON hubs, the black aluminum end cap has two flats on it. Those are for use while assembling the hub in Germany, not for user adjustments. But sometimes a mechanic will hold the hub in a vise by those flats, and grab the other end of the hub axle with some pliers or vise grips, there being no flats on the connector end of the axle. This genius doesn’t stop to think why there are no adjustment flats on the electrical end. The brilliant mechanical wizard then turns the electrical end of the axle, in a vain attempt to loosen the bearings. Well, all this does is break the electrical connections inside the hub, making it useless for powering a light, though it will still work just fine as a front bicycle hub. It also voids the five year warrantee. You will have to send the hub to me for a complete rebuild, (assuming you want the lights to work again) which will set you back $ 60.00 plus return shipping.
The point of this poignant little morality tale is quite simple. Leave the hub alone! If you bring your bike into your local shop for a tune-up, tell the mechanic to leave the hub alone! If the mechanic thinks he knows better than anyone else about how the axle on a SON hub should feel when turned, find yourself another bike mechanic. Only if you hear a scraping sound (an extremely rare condition which means there’s corrosion on the dynamo core) while turning the axle does the hub require service. And neither you nor your local shop will be able to perform that service.
