When I talk about a problem with no solution, it refers to finding the fault in this power supply and fixing it.
Apart from this, of course, there are always solutions, for example, to buy another oscilloscope.
Replacing everything is not that easy, for example, the transformer certainly should not be easy to find.
There is essential information that you are not able to provide.
1) is the overcurrent which causes the fuse to burn a current between phase / phase or phase / neutral or a current between phase / earth?
2) how is your distribution network configured in Greece?
It is, I imagine, 220V or 230V, but is it 220V between phase and neutral or 220V between phase and phase?
3) Does your installation have protection against earth leakage currents? Find out more or go see your electrical panel.
4) Have you checked your mains voltage? Are there no transient overvoltages?
This information would be essential in trying to understand what is going on ....
Intermittent failures that occur in random times are very difficult to diagnose.
And C2 and C47, are they really X2 capacitors? Have they never been replaced?
Remove them to see if the fault continues or not without these capacitors.