The primary cause of the bulb blinking is ... the bulb is dying. Only as a secondary cause is the ballast / igniter /capacitor assembly looked at.
If changing the bulb does not solve the problem, then the ballast assembly is to blame. Since the components are sold as a set, I'd change them all. There's no point in cherry-picking components.
Theory is fine .... but my experience seems to suggest that a bad ballast will often take a good bulb down with it. You almost never have just one part fail.
