Cleaning the metal face of a Jeff Rowland Model 3


For reference, here is the unit:
https://www.hifi-advice.com/blog/jeff-rowland-company-special__trashed/jeff-rowland-power-amplifiers...
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?

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

As the OP did, I called JR at the telephone number the OP provided and received the same advice from a nice persons at JR.  The person answering the phone passed me to a person in shipping who said they use that product: 
"spray it on and the stuff, tape and such, just comes right off".  I am not holding them to any responsibility if it doesn't work but was nice to know JR works like a small company where people all over the org will speak with customers trying to give a solution.  Thank you idfnl