HP 8360 - Manual (Page 459)

How to Clean the Clean the cabinet using a damp cloth only.
Cabinet
How to Clean the The display of the synthesizer is protected by a plastic display filter.
Display Filter To clean the display filter, use mild soap or detergent and water, or
a commercial window cleaner (ammonia does not hurt the plastic
surface). Use a soft, lint-free cloth. Do not use abrasive cleaners,
tissues or paper towels, which can scratch the plastic.
4-6 Operator’s Check/Routine Maintenance Specifications