[Dan Walker]

You are right Arran. The original knobs did not have the metal inserts in them and when I put some in they did not fit properly.
I had this set of RCA knobs and they work quite well.  {I just can't fool you guys}
  The 683 does have the right knobs, at least they came with those ones.
 The photo in Radio attic archives show's the wrong ones  and whoever owns that radio  probably
 did the same thing as I did.
  We had a discussion about this on ARF and the knobs on the 683 are probably the same  as  TV knobs.
 Here is the radio attic photo