If possible, find a known good igniter / CDI and swap it out to test yours. If yours is bad, ask a dealer to put it through to Triumph as a "*goodwill claim." You often don't get this facet of extended & semi secret Triumph warranty unless you ask for it specifically.
Triumph replaced mine in the manner described above well after the original warranty had expired, saving me over $500. I had two dealers withhold the "goodwill claim" and found out about it by asking a 3rd dealer. The 3rd dealer did it via phone at 100 plus miles away, and didn't need the old igniter or proof of failure.
Can't hurt to ask...
*While pursuing my warped front rotors issue, a 4th dealer 150 miles from the 3rd dealer also used the phrase "goodwill claim" when referring to Triumph honoring out of warranty problems.
If memory serves, Terry/Snert from SW PA has had 5 or 6 igniters replaced for free long out of warranty. (I think he's spilling Oonse on them) I have a feeling the dealers gets paid for a little bit of labor to change the CDI via a goodwill claim, making it worth their time to try. I could be wrong. I figure since it was free, I can change it myself quick enough anyway. I was just glad to have it for free.