Cleaning the metal face of a Jeff Rowland Model 3

For reference, here is the unit:
Anyone know how to clean one of these metal faces?  Mine has a couple of splotches.
Also, anyone know if you can replace the faceplate of a Rowland with the newer polished look?

I'd ask Jeff. If you call, his assistant will put you through to him.
Phone: +1 719-473-1181
Thank you, I called and spoke to a nice lady. They use a product called "Original Bike Spirits Spray Cleaner & Polish"
The modern metal face is not available for the Model 3.
GooGone? Do you really expect to have adhesive residue, crayon, and food stuck to your amp?

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I have successfully used womens gentle face cleanser to remove grease marks from anodised faceplates without damaging the surface.