Now that I have a plan of action for restoring the doors, I was anxious to put the hardware back on the one completed door. I assumed with dark brown doors the mortice lock plate was bronze or some other dark metal. NOT! A few wipes with metal cleaner revealed gold/brass finish, so the wipes turned into scrubs.
I don’t think anything about this project is going to be simple and quick. I was fearful to soak the lock or the glass door knob in any type of solution (thought about the vinegar method) for fear of damaging either. I used Amway’s Metal Cleaner and Brasso. Both worked about the same; both needed a steel brush scrub to get to the finish line. I may try Tarn X. One of my new, favorite, HGTV shows, Bargain Mansions, talked about a mixture of baking soda and lemon juice to remove tarnish. I had neither in my house, but I may try that too.