I have about 12 antiques mortises- they measure- 5 1/4" X 7/8" face plate, 3 3/8" X 3 5/8" case, 2 3/8" backset and 2 3/4" spacing. It is a brass faceplate, the case is black with a raised bump with a number inset in a circle(number 3 on this particular one), next to the raised bump is a 5 point star. If anyone has any clue about manufacturer it would be greatly appreciated. Thank you for any help.
Also- if anyone has any pointers about cleaning OLD brass, it would be much appreciated.