Originally Posted by
grumpus
If the bearing surfaces aren't totally trashed I would try reusing the headset but with loose balls instead of caged. A bit of roughness is OK as long as it's not loose or so notchy that you have "indexed steering" which interferes with bike handling. That's just as a stop gap, if the bike turns out to be viable it should probably have a new headset.
Exactly. The only purpose of the retainer/cage is to make assembly easier at the factory and to prevent putting too many bearings in the HS. Hold the bearings in place with grease during assembly and if the cups and cones are OK, your headset will be fine. And be sure to heavily grease the threads during reassembly.