Hi Peter,
I do not know how to remove the power window winder, but when I bought my 410 decades ago, it came with the original motors having been removed and replaced (probably with something American as I bought the car in Oregon).
While the car is long gone, the motors, including a manual winder came with the container in 1997 and is still here. Click to zoom the photo (which is the front and the back... for two front windows.
Window-Motor.jpg
Not sure if these photos are helpful to see how they were held in, but it looks primitive enough to just be some bolts and nuts.
Also, if anyone is interested in buying them, make me an offer.
Claude