You may have a riding turn on the drum. This will almost certainly cause it to trip out. If you can completely unwind the cord, keeping it under tension, there is a magnet in the cord which operates a switch which will stop it from completely de-spooling. Then wind it up again, keeping the tension on, and that should clear the riding turn. I had the whole thing off during the summer as I had a similar problem and worked out how it works. There is a simple mechanism inside which lays the cord back and forth neatly over the drum when winding or unwinding it. If you let the transom down with the cord still under tension and not supported by the grey lines each end, and then tread on the transom, you will almost certainly end up with a riding turn as the cord is pulled between other turns on the drum which jams it. I have marked the cord with a Sharpie at the point it is just past the tension point as it exits the stern. Hope this helps and you don’t have to remove it – it’s a sod! There is a manual for it on Lewmar’s website.
The membership association for owners of Dufour Yachts