DAB / FM alarm clock radio. (West Farleigh ME15)

We have a battery/mains powered alarm clock radio made by Majority. It receives DAB and FM stations and works fine on mains. The case is made of a plastic that seems to become sticky with age. I've tried polishing it with Mr Sheen but it still comes up the same. It doesn't affect the operation of the device at all. Would make a great radio for a workshop, garage or shed.