I recently bought an Open Pro wheelset with Dura-Ace HB-7600 hubs for $275 (steal right?). They seemed pretty smooth at first, but when I got home, I noticed there were some problems in the hubs. When the rear wheel was spun, it ran smooth, but I can hear very subtle "cracking" sounds. When I spin the front wheel, it just doesn't want to spin at all and feels like there is a lot of dirt inside. I think it would be appropriate to upgrade both front and rear bearings, but before I do that, I want to clean out the internals to see if it makes a big difference. Are there any tips/videos on disassembling these hubs? What sealed bearings can I use instead of the unsealed bearings that come stock, if any?