Nostalgic EF50 TRF

[Amie]

....do you where one can obtain the clamping screw rings that were used to
hold the EF50's firmly in their holders?

If you have no luck with finding the base clamps I've seen suitably sized metal caps from glass jars or similar with expansion springs used to hold them in place. Dad had a three valve TRF with a vertical chassis that had been modified thus.

Thanks,
Amie.