Somehow, everything I fix ends up far uglier than it was when I started. But, I thought, what if I start with ugly? I tested the theory by rewiring an old lamp. I first sought counsel from experts.

1. Disassemble the lamp by unscrewing or pulling the headpiece off and removing the plastic base. Buy a quick plug and a new length of electrical wire, and splice and strip a half-inch at one end.

Restoration and Design Studio owner Paul Karner’s decades of lamp-wrangling experience have given him the skills to, say, outfit an antique floor lamp with a nine-way switch or convert a candlelit ...