Hello from sunny London!
Well done on repairing your Tizio……not easy!
I have been repairng these for some years and there are many many reasons that a Tizio will flicker or fail to work.
It can sometimes be as easy as a loose stud, such as yours, or it may be as simple as a failed internal fuse.
With older 1960′s models it is often the transformer / switch. Or a failur in the head caused by loose connections arcing across the tie bar.
I’m happy to advise anyone by email, or if in London bring it to me, but call first.
You can contact me at Artemide GB Ltd – 0207-631-5200