Actually, I've used ones that don't even need soldering.
http://www.leviton.com/OA_HTML/Secti...?section=47454
The problem is, it's "mostly" on -- not getting a good connection. The socket is recessed in a metal collar (which has prevented me from using CFL and LED bulbs) and is pretty inaccessible without the right tool. I've replaced lamp sockets on more conventional lamps, but this one isn't like anything I've seen. And I'd rather pay to get it repaired thanbother with it myself.