Freeing Frozen Knobs

Sun Apr 1 19:17:44 EDT 2001

Try to free the knob a little at a time to avoid breaking things. With
patience and a little judicious application of force most will yield. Try to
look in the set screw hole to see if there is a burr on the shaft preventing
movement. Most set screws are "cup" shaped on the end to get a bite on the
shaft when tightened securely. The metal pushed up on the shaft will
sometimes prevent the knob from moving. If this is the case you can get
another set screw (Allen hex drive type) and carefully grind the end flat
while holding it steady on the end of an Allen wrench on a grinding wheel
followed by a light polishing to get it smooth (I use a sheet of 600 grit on
a good flat surface). Try to hold it square and keep it steady as you go to
get a good flat smooth surface. You now have a tool that can be used to push
the burr back down and restore the surface of the shaft. Install the
substitute screw and position it over the damaged area and gradually tighten
as you work the knob back and forth. You may have to hold the control or
control shaft from behind if accessible but you will feel it try to free up.
I use this method on most knobs that have to come off if I feel the burr in
there. If you don't the burr will gouge away at the bushing of the knob as
you force it off. Of course the damage this does is minor but I always try to
get things apart carefully whenever possible. Penetrating oil was mentioned
and of course lubrication will help. As a last resort you could always cut
the knob off. I had to do that on an SX-23 once where the shaft had rusted
inside the knob. I tried everything that was mentioned earlier by everyone
for about a week but finally gave in and got out the Dremel tool and with the
2" carbide cutoff wheel and after about 15 minutes the stubborn knob was

73, Greg Gore; WA1KBQ

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