yes they are replaceable.
getting them out took me a while to work out.
remove the cones and axle, the silver bits with the four notches in are just covers over the cone nuts but have to be unscrewed. usually to knock the bearings out I would use a piece of steel rod I have and put through one bearing to sit on the inside shoulder of the one on the opposite side and hit it out with a rubber mallet. unfortunately, there is no bearing shoulder to catch as it is flush with the inside of the hub.
so here is the clever bit
buy some M8 anchor bolts.
place in the centre of the bearing and tighten up to securely hold the bearing. hold shaft with pliers and tighten nut with a spanner. next I put the bar through from the otherside and hit it out. removed the anchor bolt from bearing and repeated on the other side.
you should be able to get the bearing code from the ones you remove, cant remember code of top of my head.
I then got replacements from an engineering place near my house. let me know if you need any getting. they cost about £16 for 4. I used a socket the same diameter as the bearing as a drift to knock the new ones in with a rubber mallet.
my hubs have been as smooth as babies bottom since.
hope the above makes sense. pm me if you have any probs
