Karcher window vacuum wv2 (Caldy Valley CH3)

This is about 10 years old and works fine except the rubber stopper has stopped staying in place. This is needed for the vacuum seal to work properly. I have tried using a rubber band but this doesn’t work well and a new stopper is £15 so it’s not worth it, but if anyone wants this because they have a faulty kit but working stopper or can be bothered to hold the stopper with their thumb then they are welcome to it.