I discovered that my Pfaff 2140's foot pedal works with my Pfaff 2040, BUT the Pfaff 2040's doesn't work with the Pfaff 2140. I ALMOST took the 2140 to the dealer to find out what was wrong with it.
Anyone who has had more than 1 Pfaff in the last 12 or so years knows that the foot pedals and their connection to the machine look IDENTICAL, and they don't have ANYTHING identifying the model they belong to. Mine do NOW in big black Sharpie numbers!