I have a Nardi unit and found the hinge (including drawings to ensure correct selection) on http://www.conigroup.it/hinges/ingol.htm
I was referred to Appliance Care (0870 9099100) for new hinges.
It is usually much easier to replace than repair.
If possible give Appliance Care the model number of the unit (usually on the back of the unit).
Howard
October 2005