My CTC-16XL Project.

[trinescope]

It's possible that there is IF misalignment which can cause a no color condition if somehow the high video frequencies (where the color information lies) are being attenuated. The only sure way to know is to attempt the alignment procedure with proper equipment, in this case a sweep generator, preferably with frequency markers. This kind of equipment should be available cheaply all over ebay these days since they're no longer useful for servicing modern sets.

You are going to need to do some troubleshooting in addition to shotgun parts replacement if you want to find and fix the problems you are having. The CTC16 is capable of pretty good performance when set up right, I had one about 30 years ago that played really well, so you'll get yours working in time. The fact that you get color with an injected video signal tells me your problem is with the tuner or IF stages, so focus your troubleshooting over there.