[Zeke]

I'm as perplexed about this as anyone. However, after reading about the wire/string idea, I thought I'd share this: when rewiring an old lamp or light fixture with a lot of curves in the tubing supporting the sockets, I use a long lamp chain and a vacuum to get a pull wire in there.

It's already been mentioned that a flexible cable like a bicycle brake cable will have the strength to pull. The lamp chain will break with not much force but it will go around some pretty tight and complicated lamp designs.

There are many lubes for these projects so I'll leave it at that.