09-17-2016, 04:48 AM
I don't own one of these sets but from what I read the earlier tombstone version used a two speed tuning mechanism where you would pull out the knob for fine tuning, all the later versions of the 16/116 used two concentric knobs with the center knob used for fine tuning, so it would make sense that it would have a set screw to hold it on the shaft for the earlier type. I couldn't tell you whether the large hex knob with the set screw or the smaller one with the tapered back and and set screw is the proper knob.
Regards
Arran
Regards
Arran