[Username1]

Crystals hold a very fixed, and very steady frequency. If the number of color bars increases or decreases wildly, then it may be the crystal. It may be the crystal if it is very far off frequency and you can't get it back on.... Lets put the crystal aside for now. They are not set specific, so one temporarily swiped from another set will be fine. No polarity either.

While I have not worked on a ctc 15, It sounds like "old coot" has, follow his advice and adjust that coil he identified, if you have the plastic tool. Its plastic so its material does not effect the coil. If it were metal, like the iron core you will be adjusting, the tool itself would change the value of the coil as you put the tool inside the coil. The coil will have a center shape like an allen wrench.

Adjusting that coil will either increase the number of color bars, or decrease the number of bars.... You want to reduce them unitll the color locks, similar to horizontal hold. If you can not achieve a stable lock with adjustment, then you have a bad component, resistor, tube, cap.

One thing you can do is to run the set, and spray a little freeze spray on some components around the crystal, to see if you can find a sensitive part, it may be bad. Long shot, and don't waste the entire can. Just a drop or two on components you know are in the color circuit. Don't spray tubes. Freeze spray is a good tool to have, also called component cooler, also ust to be available at radio shack. Maybe also available on ebay.

Be careful when re-capping in the color area, those caps are tight tolerance. Better to try and find the bad parts.

Also see if you can get a schematic from someone here, or ebay, and begin to learn about these circuits so you have some idea about recognizing the parts, and parts of each circuit that depend on the previous circuit for the set to function properly. Sam's have lots of cool stuff in them, even if they are not perfect.

Have a good night....