I inherited a box of machinist tools from my Grandfather. I was going through them a bit to figure out what I have and there are alot of Starrett tools which is nice. One of the items is a Starrett Last Word indicator probably hasn't been used in 40 years and the dial sticks. Is there a safe way to clean it without messing it up?? I thought about putting it in a Sonic cleaner I have that is filled with Simple green but I didn't know if it would mess it up. Any help would be greatly appreciated. I am a serious beginner to this and am teaching myself as I go (I know nothing) I have a Grizzly G0704 mill and an old Atlas 618 Lathe I've been collecting pieces for and still need to set up. Always was interested in this type of stuff and want to be able to make small parts.