I pulled apart my Onyx Classic 6-bolt rear hub to service it. There was no grease under the end caps, and there was dirt on both outer faces of the bearings, which I cleaned off.
I pushed the axle out, then I pulled the freehub out of the hub body just like in the service videos. The extension protruding inward from the freehub had a lot of grease on it, and the grease was wet, clean, and tinged dark brown (Kuber Isoflex?). The service videos don't show any grease on there.
None of the collets for my slide hammer would fit the drive side bearing--one was about half a millimeter too big, and the next smaller collet was way too small, so I used an expanding type bearing puller, which only grips the inside of the bearing, and you tap it out from the other side of the hub. I purchased the tool from bearingprotools.com. Confoundingly, the drive side bearing was a 6805 bearing--not the 6902 claimed by Onyx.
(6805 bearing puller on the left, press on the right)
The DS bearing has an orange seal that faces outwards, which says:
And on the edge of the inner race facing outwards it says:
Onyx Racing Ceramic Balls
On the inside face of the bearing, there is a black seal, which says:
I removed the orange seal with a pick to service the ball bearings, but the grease was wet, clean, and plentiful; so I put the seal back on without doing anything.
After tapping out the DS bearing, I removed the cir-clip, which allowed the spragues to slide out. Both of them were wet with clean grease, and they didn't need servicing. I serviced them anyway. I didn't want to use the toxic mineral spirits shown in the service video, then have to take the used portion to a hazardous waste dump, so I soaked the spragues in isopropyl alcohol, and I used an old toothbrush to clean them. I ordered the special Kuber Isoflex grease about 6 months after buying my hubs, and now 4-5 years later, I noticed it's not the right kind. I don't know if I ordered the wrong item, or the vendor shipped the wrong item, but I've got Kuber Isoflex NBU 15, so I went online and I ordered the correct Kuber Isoflex LDS 18 Special A. Expensive mistake.
On the NDS, the bearing has an orange seal facing outwards, which says:
The bearing in the middle of the hub has a snap ring holding it in place, which you access from the NDS. On the black bearing seal, it says:
The black seal faces the DS, and there is an orange seal that faces the NDS. If you were to remove the snap ring, I don't see any reason way you couldn't pull that bearing out the DS.
The Shimano compatible freehub has a bearing with an orange seal facing outwards, which says:
I stuck my finger through the middle of each bearing, and they all felt smooth when I rotated my finger.
Once the special Kuber Isoflex grease arrived, I put some on the spragues. I tried putting a glob of the Kuber Isoflex on top of the inner bearing, but it was hard to apply anything but a thin layer of grease. Then I reinstalled the spragues (teeth facing counter-clockwise), but I had a little trouble getting the cir-clip back in--eventually I got it to seat in its shallow groove above the spragues.
Then I pressed the DS bearing back in. I didn't have anything to brace against the opposite side of the hub. Everything I had was too small in diameter, and therefore I would have been bracing against the inner race of the bearing or the ball bearings themselves. I finally managed to jam a female cup for a bearing extractor into the opening on the NDS, so that I was bracing against the outer race of the bearing, and after pressing in the bearing on the DS, I had a hard time getting the cup back out. I will have to order a 6804 bearing extractor and press.
Unlike in the service video, I waited until after I inserted the axle through the hub body to apply loctite to the threads at the end of the axle. Then I carefully applied some sticky marine grease under both end caps, and I reinstalled the end caps. The axle felt a little tight when I spun it with my fingers, which I expected might be the case after reinstalling the bearing, so I set about to adjust the bearing preload.
I removed the NDS end cap, and I loosened the screw on the preload collar, but the sticky marine grease seemed to prevent me from setting the preload correctly and getting the axle to spin easily. So I removed both end caps, and I removed the axle, and I cleaned off all the sticky marine grease I had applied. Then I reinstalled the axle, and I applied loctite to the threads at the end of the axle. I think I could have gone ahead and installed the end caps without any grease under them--they don't say to apply grease in the service video--but I decided to apply some Slick Honey, a much lighter, thinner grease than the sticky marine grease I used previously. That seemed to work well, and I eventually got the preload collar adjusted: I tightened the preload collar by hand, and as soon as it met any resistance, I found I had to back off the preload collar about 1/4-1/3 of a turn to get the axle to spin smoothly--more than they show in the service video.