Glad to hear it SS.
I'm guessing just a little, but I'd bet a
pound to a penny that if you peer into the old PSU you'll find the electrolytic capacitors are bulging. It's the one component the electronics industry has failed to get right, despite the fact they've been making them for over half a century.
In switch mode power supplies, the circuits stop working properly if the parameters (ESR in particular) of the capacitors drift too far out of tolerance, often manifested as lazy start-up and easy overloading. Failure of other components tends (usually) to lead to a more absolute failure. Even then, the failure of other components can often be traced back to increased stress caused by a failed cap' or two.
Since this PSU's not completely dead, replacement of these cap's (a few tens of pence each) is probably all that is needed to restore health, though with labour costs it's unlikely to be a cost-effective option unless there's any special reason you want to keep it. You may also struggle to find anybody willing do do the work, unless you can DIY. On the brighter side, even though a capacitor may be well within it's temperature rating, it's life doubles for every 10 degrees further reduction in temperature so these noisier fans may be doing more good than is apparent.
Cap's are an ongoing gripe of mine, just thought I'd get it off my chest
