Single spark. Then nothing.

It definitely sounds like you have an issue with the TCI box. Repair can be attempted, if you have some experience with soldering electronic circuit boards. But first, go through and make sure all of the TCI electrical connector contacts are shiny and clean and try things again.

If you don't want to try and fix your TCI, start looking for a replacement one on the marketplaces. There are two different "styles" - the older board from the 1980 bikes and a simplified board that was used in the 1981 and 1982 SOHC bikes. Either type of box will work as a replacement as they have the same connections and functionally are the same.

If you want to try and fix the TCI you have, I have some thoughts on what you should do, and I know others who contribute here have ideas as well. I have been preparing for the day I might have to do this to my TCI. We can point you to some old threads to read and pass on whatever info we have on the subject.

One question - is your TCI one that you got with the bike or did you get it to go with your "new" harness?

 

Sounds like a solid plan. Fingers are crossed here hoping the new box is a good one. Please let us know how things shake out once you get to try the new TCI. Also, don't toss the old one, someone may need that to fix, eventually.

 

It's not supposed to make contact, just pass by very close so as to induce a magnetic pulse. Maybe try loosening the pickup and shifting it to even up the gap between both pickup points?