I was trying to clean some label goo off of a calculator display recently, and "Goo Gone" wasn't doing it alone, while I was afraid to use a fingernail.

I ended up retrieving a used fabric softener sheet from a laundry basket. After most of the aromatics have been boiled away, the softener sheets' substrate is like a loose, random nylon (or ???) mesh, with a very slightly abrasive quality.

Along with Goo Gone, it worked like a charm, and it was free. ("Free", that is, if someone near you uses fabric softener sheets in the dryer.)

FWIW

And the fresh, clean, smell of the calculator after this application is nice too!!
;)