Your red gun is absolutely fine. The first and third shots show plenty of red and look pretty close to what I'd call watchable.
The CT-100 I had, that's now John Estep's, had a green gun that would take a touch longer to wake up than the other two guns. By the time I sold it to John, the green gun was coming to life right in step with the red and blue. I'm guessing in both of our cases, very mild cathode poisoning from ~60 years of non-use was to blame.