[TowerTalk] Cable noise (?) on UST crank up

[Richard (Rick) Karlquist]

My UST HDX-5106 makes "popping" or "creaking" noise when
being raised.  (Mainly raising, only occasional noise is
heard going down).  It seems to be from the cables being
stressed, just going by the sound.  I frequently raise the tower to
a particular point half way up.  Less frequently, I raise
it all the way up.  The tower is quiet up to half way
up and starts making noise above that.  By exercising it
more in the upper elevations, it has gotten less noisy.
The last 5 or so feet has been problematical, sounding
like something was going to seriously break down or bind.
Whatever the noise is (hard to describe, you would have
to hear it), it seems to be specific to which sections of
the cables are going over the pulleys.  I am wondering if
I need to use cable lube to get rid of the noise.  Is
cable lube actually a lubricant or just a moisture displacement?
Sometimes the tower makes such loud noises that I stop the motor
and back down the tower a few inches.  Then I start back up
and the noise is gone at the height when it just occurred.
I am afraid to just let the tower work its way through the
noise because it may be indicative of some serious malfunction.
Alternately, make the tower sections are binding and it just
sounds like the cables are being twanged.  However, wind
speed doesn't seem to affect the problem.  The cables look
fine visually and aren't rusted.  The pulley bearings are
an unknown, but it seems like they should be the same at
any height.  The tower is 15 to 20 years old (guessing,
I didn't buy it new).  Should I be replacing the pulleys?
Many comments have been made about cables lasting virtually
forever, but pulley bearings?

Can anyone shed any light on this?

Rick N6RK