The CT-1 uses an oscillator tuned to approximately 19 MHz for the open test.
It does not matter if it is 21 MHz or 17 MHz, and there will be no
difference between a 5 pf or a 10 pf or no pf across the coil.

If no one got offended, I would say that you are barking up the wrong tree.
But, I do not want to hurt anyone's feelings, so I will not say that. My
dog would not get her feelings hurt if I talked like that to her, but people
do.

The problem is elsewhere.

One of the problems, when you pick up something that does not work, is
assuming that it ever worked. Sometimes kits were assembled, and did not
work, then put on the shelf where they languished for decades.

Check the wiring and check to see if the oscillator is oscillating.
Sometimes switch contacts are wired incorectly. Sometimes switches are
improperly cleaned then fail Sometimes resistors fail.

In the past, we check the paper and electrolytic caps. Now, we may need to
check the mica caps.

Colin K7FM