Trouble with Goldring 1042

Yes the mounting hardware is white nylon plastic. I never used this type of hardware until earlier this year. Before that I always used aluminum or whatever the manufacturer of the cartridge provided. I starting using this hardware because many Stanton users swear by it. With a Stanton, you either have to use these hard black plastic mounting blocks or the "double nut" technique with nylon hardware otherwise you can have a grounding issue. I had a hard time with the mounting blocks so I tried the nylon and it worked for me. 

The reason I put the nylon hardware on the Goldring is because the body design makes it hard to use many types of screws with this cartridge. I had several sets of different hardware on hand and this is the only one that worked for headshell. Too short, and it won't fit a thicker headshell. Too long, and you can't get the nuts on the screw because the body blocks you from doing that. Try it upside down, the screw heads are too big and won't fit. With the nylon hardware, the screw heads are a little smaller and I was able to get them to work upside down with the nuts on top. Many other cartridge manufacturers give more clearance around the body so it's not so difficult to use different types and sizes of hardware. 

In terms of the coupling/decoupling thing, I have no idea, but I have not had any problems using nylon hardware. Some folks have mentioned that it in some cases, it may come loose due to vibration and throw off your alignment. I haven't had that problem though. 

I have always used brass/nickel ones and wonder if anyone has undertaken any sonic tests between them?

My fuzzy logic would suggest that metal are likely to be more rigid, can be tightened more firmly but plastic would provide a decoupling effect?  

I have rarely seen arm components screwed together with plastic fittings.