Since posing the symptoms and the questions, I have found the source of the leak which turned out to be the hose from the base of the heating column / chamber and the first pump. The hose had come adrift from the input spigot of the pump and filled the drip tray which then allowed water to leak onto the floor.
After refitting the hose ( can't understand how it came off in the first place ) I thoroughly dried the tray, turned the water supply on and switched on at the wall.
After pressing the "On" button on the machine, the inlet /outlet light was a constant red. I turned it off by pressing and holding the start button until the light went out.
About 10 to 15 seconds.
I answered my other question regarding access to the pumps :-
Unplugged machine from wall socket.
Shut off water supply.
Unhooked drain hose from under the sink.
Pulled machine out from under the worktop.
Removed the top panel, (access to 2 screws from underneath, with the door open) then slid the panel back a little to clear the 2 retainers at the back.
Removed both side panels (each with 2 screws at top, 1 screw at front with door open).
This allowed access to view the tray and at this stage managed to refit the hose.
Regarding access to most of the components above the base tray, I suspect that for ease and safety, complete draining will be required then the machine could be carefully put on its back ( inlet and drain hoses to be positioned to avoid being trapped or squashed) to allow the bottom panel to be removed.
syltonian55
April 2012