I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have shown
that the adhesive used to fix the chrome trim has affected the material and
caused the knob to fracture after a period of time. A further investigation
by the manufacturers disclosed that the material used in one batch of knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/