Thanks for that info. As the fault is no longer there, the solder must have been the problem, and I understand from elsewhere that this fault is known and Ford will replace the whole unit at a reduced charge. I haven't heard that they will also replace the VSS. I wouldn't want to discourage owners to try my fix just because something else might go wrong in the future, and it is something you can do with no expense.I doubt if a main dealer would resort to a soldering iron.
Ido appreciate the info though. I love the idea of a knowledgebase like this. When I was young we just had to resort to a Haynes manual with a picture of some bloke holding a spanner, as if this was any help.