Very nice to hear from a fellow dutchman who loves these beautiful trucks Robby!!
I have the same problem with the wipers only going down when i turn the switch off.
The damaged part from your motor makes the vacuum switch. I know for a fact that parts for these motors aren't available on any dutch website. I would suggest to take the good one apart (or glue this one back together), trace the part on a piece of wood with the same thickness and cut/drill it out. I think it is easy to remake that part when you are a bit handy.
How far does your wiper go over your center post? Mine also goes a little bit over the rubber (that holds the center piece in) when its almost completely down. I don't find it a very big problem as long it wipes the glass.
