[Arran]

Ron;
  Got to love those wire nuts, wrong, but still better then just twisting the wires together and covering them with 1/2 a roll of tape. As long as the new thicker wire fits through the holes in the speaker socket it will be fine. Do you know what gauge the AES cloth wire is? I'm wondering how it would compare to the stuff that Tom's Engine Barn sells, I think that the smallest they sell might be 18 Guage, but they also have more variety in colours then most places offer, such as wires with tracers on them. With regard to the rivoted on insulator there is also the option of drilling out the Bakelite and tapping the hole for a fine threaded, flat head machine screw, if the rivot had not come out.
Regards
Arran