946 Alfa Romeo Spider with drivers window error

We have recently fixed a customers car with a random drivers window fault.The window should drop app 3 cm when the drivers door is opened and the close once the door is shut.The fault with the car was that the window would drop to various heights and once opening fully and refusing to close lading to a visit from the AA.Unfortunatley this problem is very rare,our latest Alfa Witech tester would only narrow it down to two items,a visit to an Alfa dealer also only narrowed it down to the two same items.From here its a process of elimination time and patience.Finally the fault was traced to the door node.We are sure it must do more than control the window for the amount of electronics inside the unit.There is one unit per door - to think the 916 Spider just had a micro switch to control the window operated off the door lock  - progress ????