Okay this is my last post here.
I finally had my "Eureka" moment. The problem is the microswitch in the door catch.
The microswitch has somehow changed from "normally closed" to "normally open" which is really odd. It is a bit blackened on one end, indicating that it has blown in some way, probably someone opened the door just before the cycle had ended, causing the fault.
However, the door catch is designed to hold the button on the switch down until the door closes, at which point the button is released. So if you can get your head round this logic (no mean feat), when the door closes, the button is released, allowing the switch to go into its normal state - closed, allowing the cycle to begin.
In its faulty state the switch will only let the cycle begin if the door is open, so I can wash the dishes if I don't mind flooding the kitchen at the same time, leaving the door open!
How did I discover this? If you read one of my earlier posts I couldn't understand why my machine suddenly worked, then didn't. I retraced my steps and realised that I had detached the door catch while I had the "front (panel) off". With the door held closed it worked perfectly! The solution was right under my nose but I didn't spot it at the time!
Gerry
February 2008