Being able to heat and bend will depend on the polymer that are made from, thermoplastic can be remelted and reshaped or softened and manipulated but thermoset polymer cannot.
If it is a thermoplastic my guess would be ABS (acrylonitrile butadiene styrene) which has a softening point of 105 degrees c, but the cable within is probably insulated with PVC and can only withstand temps of upto 85 deg c, so if applying heat would be prudent to remove cables from the stalks and as you said some sacrificial parts to practice on is a must. I would think there are plenty of parts available on line to practice on as plenty of old discos on the scrap heap.
Good luck and would be interested to know how you get on.
Would think also that the material used would be on all models regardless of year.
Andy.
Last edited by Andy Ed; 07/11/18 07:10 PM. Reason: Paragraph added and signed
