There has been a lot of talk about how old 558 is but not how new she is for indeed she exhibits identical issues with new aircraft.
All aircraft exhibit the same serviceability trends. It is designed and built but even with modern techniques much work has to be done ironing out bugs. Initial serviceability is bad with a single aircraft often grounded for weeks.
Once it enters service new issues are found as newer aircrew and engineers gether hands on it and find new ways to break it. After a couple of years its quirks and vices are tamed and it becomes more reliable.
After many years service it is seem as a reliable workhorse and eventually retired or, as happens with many UK military aircraft, its service life is extended passed any originally conceivable end date and its serviceability again becomes an issue with experienced engineers nursing it along.
The question is where the Vulcan is on this model. In some instances it must be at the beginning of its life as there are few experienced type engineers used to operating the Vulcan - note I am talking about flight-line knowledge and not factory floor. On the other it might be considered beyond the end of its service-life.
I submit that it is nearer the begining than the end with the only consideration is not using the latest technology in its build.