Thanks everyone for your help. I did search the Whirlpool site and as I said, they just led to the operating instructions. You have all been 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} more helpful than them!
Your advice Spimps is spot on and makes complete sense, and yes Kwatt, it is those things! I have been trying to them without breaking them. At least I know I can get replacements if it goes wrong!
From what you say it looks as if the screws are on the inside of the door. I will arm myself with a tape measure and screwdriver over the weekend and let you know how I get on.