Arnold: I've had the same sad experiences as you, and I've also had inquiries from customers asking about the suitability of our cartridges for use with polystyrene records. I have therefore looked into the matter in some detail.
But I don't use Gyger stylii in production, and my hand-on experience with stylii with side radii in the 5~6um range is not as extensive as side radii in the 2.5~3um range. I _believe_ that 5~6um is large enough for molded styrene records, but perhaps larger side radii are more suitable. If other Audiogoners have experiences with Gyger stylii (or other stylii with side radii in the 5~6um range) on styrene records, I would very much appreciate hearing about those experiences.
Don, AFAIR, molded styrene was used primarily by Columbia Records for doughnut 45rpm singles which were manufactured in the mid-60s. If any one else can add to this information or correct it if it is wrong, I would appreciate it.
best to all, jonathan carr