The dynamotor pins are  about the size of a mini-banana plug.  I bought a bunch about 10 year ago to make my own cables to fit a ARC 5 mod/dynamotor, potting them with epoxy in a round holder.  They fit in tightly, but they did go in. While I could never find the ones that had a solder cup, these all had 4-48 nuts and washers for the threaded stud on them.  You might try starting here for the correct size:  file:///C:/Users/Libertos/Downloads/d3276-4513_105_4.pdf

Charlie, W4MEC in NC