Best method of cleaning thin layer of degraded plastic?

[Jonathan Busby]

I have a number of old electronic devices whose enclosures are made of plastic and said plastic has degraded over time leaving a discolored sticky residue in the upper < 1mm of the plastic. I've used "CRC Electrical Grade 2-26 Plastic Safe Cleaner / Lubricant" ( see here ). I've also used "Goop" multipurpose cleaner, but I don't really like it as it has lanolin in it ( ie. sheep sebum :| -- disgusting :| ) which tends to leave a residue on the plastic. Does anyone have a recommendation for a better method of cleaning off the top layer of degraded plastic on an enclosure for an electronic device ( especially old vintage and calculator devices )?

Regards,

Jonathan