I posted this question on the Williams yahoo group and received this reply:

>Well, on my machine it says "T.M." and is actually a small, clear sticker
>with black lettering and not actually painted on. The size of the sticker
>is about 11/16" x 7/16". The location is right where you show it in your
>photo.
>
>Stef van Dijk
>Chapel Hill, NC