Problem is ,mine is a pressure switch,but seems to wired as per the micro switch version,strange,which is why I wondered about a replacement lid instead of the complete switch
…….contact Munster Simms and ask them if they do this spare part separately.
They have been known to send small parts out free of charge!
At the very least they will tell you how to fix your problem. http://www.whalepumps.com/
In all my years of caravanning I think Munster Simms (Whale) are one of the nicest and most helpful companies that I have ever had the pleasure of dealing with. Good honest customer service and a commitment to their products, I wish there were more about like them.