I purchased one of these over the winter - will be putting it on next week when my Key West FS219 comes out of storage...
https://minnkotamotors.johnsonoutdoors.com/accessories/trolling-motor/plug-receptacle-saltwater-mkr-24
I had to buy it through Amazon and have it shipped from the US but it appears to be well worth the $150 I had to pay for it.
Minn Kota are now looking for a new manufacturer of the plug based on feedback from Johnson.