On Saturday, June 30, 2018 at 5:46:00 PM UTC-7, Michael wrote:
I decided to change the center on my lathe and (finally) after punching the old one out, I see that there was rust on the connection.

What's the proper method for cleaning rust off a morse taper?

If it's just a little staining, rub with metal polish; I like to keep a few
rags and some Fuller Brush Co polish under the sink. If you can
hold the gizmo in a vise, a string dipped in polish, wrapped around,
is easy to get rounds shiny.

As others have mentioined, perhaps vinegar would work.