Hi, Talya, and all,
We recently worked with Scott Sweeney at Yankee Lighting Workshop (located in Wayland), and were really happy with the results. He worked on an historic sconce was able to make some old wiring operational. He is not a licensed electrician, so there are certain installation kinds of things he won't do, but lighting repairs are right in his wheelhouse. Good luck!
Meghan Gelardi Holmes
Curator
Gibson House Museum / Colonial Society of Massachusetts