[Radio Wrangler]

Some of the hard plastics are naturally too hard, to the point of brittleness which has to be moderated by the use of plasticisers. Plasticisers tend to go walkies over time, and old plastics lack the advantages of modern plasticisers.

Some plastics like polycarbonates are also diabolically sensitive to fluorocarbon solvents like freons which used to be used as aerosol cleaners and also some other cleaners. I was shown some HP plastic moulded board extractor, one quick spritz of 'Inhibisol', count to ten and then try to use them.... breaks every time! Those solvents are long outlawed but do trace amounts accumulate?

David