The community is small, but tight, everybody supports everybody else. Better, more detailed advice than mine is sure to be coming, but with the holidays good answers can take a day or two.
86 Euro is one of the best years for the 928. It has the suspension of the next model year, with the body style and engine of the early cars.
Here is a parts diagram, not too good though.
http://dcauto.gotdns.com/catalog/images/full/928_USA_83_86_KATALOG/pg_0152.jpg
Switch is 964 613 012 00
http://www.mailordercentral.com/928intl/prodinfo.asp?number=964%20613%20012%2000
It might be good if you posted your VIN or all but the last 4 digits if you want to keep it private, so we can be sure of model.