doscoloration of HP-71B's metal cover


Recently, I've got an HP-71B whose metal cover surrounding the display shows a brownish discoloration. The former owner of the machine says that this is probably due operation of the unit in a metallic protective case. I tried to get rid of this grime using both a household detergent and 94% isopropyl alcohol. Unfortunately, the results were poor and unsatisfactory! Does anyone know how to get rid of this brownish grime? Any advice would be appreciated! Thanks for your time!

Regards, Juergen


Try white gas (Coleman camping fuel). It sometimes works wonders (particularly for adhesive residues). It does not harm the plastic cases but can leave "water" marks on the keyboard background. Make sure your solvents are compatible by testing in on the back of the battery cover first.

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