Thanks to over twenty years' research, it has been possible to select the coffee machines in my collection in tip top condition, some of which were found in their original packaging, new and never used, others as if they had been removed from a coffee bar and never restored.
Many models are in an incredible state of excellence, our luck was finding them in places where there was little humidity (many coffee machines are made of materials such as copper and bronze, or brass which are highly sensitive to oxidation). The machines found in really bad condition were another kettle of fish entirely and had to be completely or partially restored. When it was not possible to find original parts, I intervened by rebuilding the parts myself, basing this work on original documents which certify the model produced.
I consider 70% of my collection to be in its original state. I do not agree with complete restoration, as you lose the traces of the wear and tear of time which make an object so charming. To give an example: a worn-out cup plate does not mean it is ruined, but rather, that it is in its original state of wear and tear.
Many collectors do not share this philosophy, but I think it's very important in order to preserve history.