Luckily, that one is nice and quiet too!

Cool, looks like new!

I'm fairly sure this one has had an easy life. These get really loud with use and this one is very quiet.

Is the increasing loudness a sign of failure to come or do they still go on?

That is one of my questions too, because the 60W circline fitting in the kitchen of my parents house sometimes has its moments of making a loud buzzing noise and then quietens

They usually tend to keep going. People tended to re gear them or replace completely once they got too loud.

The pure peace of mind you get with magnetic ballasts, they just keep going and going when looked after well, although they can take some endurance compared to electronic ballasts. This is why for any permanent ceiling installations in the house I will avoid electronic ballasted fixtures unless I can replace them fairly quickly