Cari, thanks. I forgot.
Some that I have worked on seemed to have kind of a brass finish.
You may be surprised, but indeed it does look pretty rusted. If you can, maybe some 0000 steel wool and sewing machine oil over the area might bring out some of the numbers. I'd still be tempted to let some oil sit on it for a while.
My 1912 66 had/has a different hand wheel and the low shank foot. I don't think that it originally had those. According to ISMACS the decals were used from 1902 to 1923. Also, ISMACS seem to indicate that the low shank started in 1923. Without the actual serial number, it could be anywhere in that time frame. I'm guessing that many may have come with the back clamp had the presser bar switched to accept the more prevalent low shank. I'm also not sure when the machines started to have the motor boss became standard.
At least yours still has the original hand wheel.
I'm not sure if you have read about using Tri-Flow, but it is highly recommended. I usually start out with regular sewing machine oil. I progress to Tri-Flow if I have a troublesome spot.
Janey - Neat people never make the exciting discoveries I do.