Dear Lew, To add to your thoughts or assumptions I would like to mention the fact that the original ''base'' or the collar holder is made from aluminum. Steel (hardened) from which the FR-64/66 are made is very difficut to process . This was the reason to introduce aluminum FR-64/66 models. But there was an steel kind of base
for the old FR- 64/66 as separate. The thing looks like an huge nut.
Other tonearm manufacturer also produced such ''weight addition'' to
the arm base . Probably with the intention to ''divert'' resonances
into heat which is actually the same as (resonance) ''dampening''.
The B-60 has the same function in addition to the VTA function.

