Restringing a Radio

[Ron Evans]

Here's hoping someone has dealt with this problem before and can offer
some much-needed assistance.

Recently, I restrung an old radio according to the drawing in the
operating and maintenance manual, trying my best to get the tension on
the string just right.  I used the right diameter dial cord obtained
from Antique Electronic Supply.

I was thrilled when I finally finished the job to find that everything
worked perfectly from one end of the band to the other. No slipping and
the red indicator moved up and down the band like a champ!  I set the
radio away for a couple of weeks to "stomp out some other forest fires"
around the house and then one night sat down to enjoy listening to the
receiver I had restrung.

Horror of horrors!

Turning the frequency knob resulted in "slipping" of the string on the
intricate system of pulleys and tension wheels, and the red indicator
attached to the string just sat in one place as I frantically turned the
knob. (Actually, the indicator moved about halfway down the sliderule
type dial before it began slipping and then stopped completely in
another inch or two.)

I reached inside and plucked the string with my finger and found that it
was VERY noticeably looser than when I had finished the restringing
effort a few days before.

I could only conclude that the dial cord had stretched. It was still
strung exactly right around every little wheel with the right number of
turns around each one.

Apparently, the small spring on the main pulley where everything started
and ended was unable to compensate for the stretching of the cord.

I had never restrung a radio before and didn't know what I had done
wrong. All I can think of so far is that maybe I was supposed to
"pre-stretch" the cord for a week or so before doing the restringing.
In what little I could find on the Internet and a few books I have, I
never found any reference to this "pre-stretching."

Can someone tell me if my theory is correct, and I should have
pre-stretched the dial cord?  It very definitely has stretched, but I
thought that dial cord was made in such a way to preclude that
happening.

Secondly, is there any way I can "fix" the problem OTHER THAN tearing
the old receiver down to the ground again and starting all over from
scratch?  It was a "bear" the first time, and I'm not really all that
eager to tackle the job again.  But I may have to.

Any help would be MOST appreciated!

Thanks in advance!

Ron - K5MVR  (since 1957 but feeling like a Novice! *grin*)