The part that grips the pin is made of several tiny contacts. I don't think they are gold-plated; in any case, gold would likely not fare too well in the presence of the heat generated by the 6C33C.
Image below: In the case of the Teflon sockets for the 6C33C, the Teflon plays no roll in clamping the pin; there is in fact a generous gap around the pin receptacle and all clamping force comes from the springiness of the metal contacts, which are confined by a hollow cylinder.
Next two images: The pin receptacles are composed of threaded parts, which, in my opinion, should be soldered as one to improve both electrical and thermal conductivity between the individual parts, as well as keeping them from coming loose over time.
Image below: Here is the problem with these sockets... The threads of the large pin are not long enough (not enough of them protrude through the Teflon base) to allow proper threading of the securing nut. Threads on the smaller pins are longer and the smaller assemblies can be adjusted to compensate, but as this is not an option with the large pin; thickness of the Teflon base must therefore be reduced by at least 1.5mm.
Image below: Showing material that needs to be removed to allow for short threads of large pin.
Image below: Fully assembled after Teflon base has been reduced by 1.5mm; note, even after reduction in thickness of base, there are still no excess threads protruding past the securing nuts. In the case of the ML2, the four chassis mounting holes in the Teflon base must also be enlarged.
Image below: New sockets have pin receptacles closer to the center of the socket... Lamm rightly leaves no excess length, so getting the original wires to reach the pin receptacles is tricky.
In spite of the work necessary to correct the thickness issue, I'm very happy with the results and would in fact recommend these sockets. I do nevertheless have to admit, considering the price paid (something like $38 each plus shipping and customs), that it is reasonable to expect a finished product. I assume these are among the first that the manufacturer has produced for the 6C33C, as the thickness issue could be easily corrected during future production.