[TenTec] removing knobs from TT Century 21 Digital ?!! no setscrew access

[brianpepperdine brianpepperdine]

Hi, I picked a TT Century 21 Digital up at a hamfest in 2019 and am now turning
my attention to it. Admittedly its the 3rd one to arrive here, with hopes of
turning the Digital and the 2 analog ones into one or two working rigs.

In all cases the PTO is the first thing to have to look at - frozen like Captain
Highlanders Fishsticks, HI.

OK.. take off front panel. Makes sense....  BUT.....
the small knobs don't have the set-screw hole for a screw or Allen key set-screw
access. What? One of the knobs (already showing a couple cracks/gaps) has an
access for knob release. 
But all the other main knobs (small round) don't show an access hole. How do I
get the knob off? I thought possibly (oddly and strangely) they might be
friction fit with a little metal tab holding them to the shaft tightly,  but
they don't sure seem like that.. a little bit of pulling and a bit of
screwdriver leverage (carefully.. since we know these things crack) don't seem
to show any easy friction fit release.

Anyone encounter these seemingly reluctant knobs before?
tnx
Brian VE3HI   VE3VAW