Though I've never done it I found a technique on "Bike Forums".You heat up the hub (carefully) for a few seconds with a torch, then hammer out the cup with a "blind hole bearing puller".Three questions:
How did you go about getting out the good one?
Why pull out the good one?
Where did you get replacement cups?
That does sound like a good technique unfortunatly I don't have a torch . I just sprayed wd40 in the back of the cup left it overnight then tapped it out with an allen key. I was planning on replacing both rather than just one. Haven't got replacements yet but I thought a bike shop would sell them! If not I have an old buckled wheel I could use those.
There's the problem, I looked into the same thing a while back, the way the industry is they expect the end user to buy a new hub or whole new wheel.There are NO real suppliers, not in the sense that you can buy everything else down to loose bearings.My plan was to pull the cups from an old hub and use those, but that doesn't mean they'll fit, there is no standard for cups outer diameter.I found one supplier in India, but if I remember correctly you'd have to buy a lot of cups.If we could get a group of buyers here I'd be willing to put a few bucks in for 6 or so cups for the future.New hub, pull some cups from a hub, or check with your LBS, they may have some loose.
It's not that you CAN'T get them, it's that you probably have to buy 50,000 units.You need not replace the hub, cups can be pulled and reseated, find a hub on ebay of the same make as your hub, pull the cups and press/hammer them into your wheel, there's posts on "bike forums" detailing this process.
I put in a price inquiry to a cup supplier in India just for fun,... we'll see.
Here's a quote from Sheldon Brown, "Examine the cups (in the hub shell) in the same way. In most cases it is not possible to replace the cups without replacing the whole hub, but fortunately the cups usually are the last parts to wear out. If the hub is cleaned regularly, lubricated and kept in good adjustment, the cups should last indefinitely."
Here's a quote from Sheldon Brown, "Examine the cups (in the hub shell) in the same way. In most cases it is not possible to replace the cups without replacing the whole hub, but fortunately the cups usually are the last parts to wear out. If the hub is cleaned regularly, lubricated and kept in good adjustment, the cups should last indefinitely."
I found a post on the other forum. Links to the pictures were removed, but I found a decent copy with Google Images. http://motorbicycling.com/showthread.php?t=35368 The picture is worth a thousand words.