If it "comes and goes", probably not CRT or flyback. Most likely bad solder joints in the heater circuit. The glow you see in the neck of the of the tube is the heater it needs to warm up the red, green and blue guns in the CRT. The poor connections could be on the small board on the back of the CRT or near the flyback. They could be labeled "heater", "6.3 V" or a picture of a wire in a coil shape. They may also not be labeled at all!! I can't remember on the 1084s.
