Siemens Hydro sensor, usual problem, no idea what to do next

Used this forum and its search facility to get me this far, I seem to have spent the last 6 weeks of my life reading about dirty pipes, pcb’s and 1 minute to go!!!!! But I’m now well and truly stuck and very confused.

Its the bosch/Siemens long wash cycle time and 1 minute to go “error code” again!!
This seems a very common fault with Bosch and Siemens machines so plenty of advice on the forum about what to do.

So here is what I have done so far :-
1. Checked the heating element and it reads 24 Ohms across the terminals so that’s ok.
2. Removed and thoroughly cleaned the lower ribbed feed pipe.
3. Removed, dismantled and thoroughly cleaned the water control assembly and diaphragm switch (circled in red below).
Both now as clean as when they were new.

Tested and symptoms the same, 199minutes wash cycle, no hot water, 1 hour into the cycle it still shows 199 minutes, it never seems to stop, eventually the display shows 1 minute to go hours later.

Admitted defeat and got an engineer out, he told me it must be the control PCB, he wasn’t able to repair it, so didn’t charge me.

Searched on he and found details of a Control board repair service so I removed and checked control module PCB myself, no obvious dry joints or problems but thought I worth the postage and the £5 test fee to get it checked out.
Module retuned from QER, with a number of new components on the board, total cost £55.
Replaced the unit and symptoms the same, 199minutes wash cycle, no hot water, 1 hour into the cycle it still shows 199 minutes, it never seems to stop, eventually the display shows 1 minute to go hours later. !!!!!!

Does anyone have any ideas what it might be?

The popular theory seems to be that the heater doesn’t work due to under filling. If I open the door mid cycle the water is about 1/3 of the way up the salt dispenser lid.

I tried to put more water in (about 4 litres) with a jug to see if this started the heater, no change.

I sat and videoed the first few minutes of the wash cycle (off work recovering from major surgery, so all the time in the world) to see if I could figure out how it all works.
Link to video on youtube !!

http://www.youtube.com/watch?v=HLdGLfmrAII

Large thin panel reservoir begins to fill, reaches the top, overflows down the middle chamber and past the black plastic bit inside the flow valve,
1min 24 seconds in to the video the diaphragm valve is activated as water backs up – small red button on micro switch is depressed and the volts across micro switch terminals drop to zero???

1min 48 seconds in the circulation pump starts
1min 54 seconds in the diaphragm valve is de-activated the plunger in the middle goes back in – small red button on micro switch is released and the volts across micro switch terminals rise back up to 240

The water slowly rises to level highlighted (see photo) in the chamber below the diaphragm switch and this stays fairly static from then on.
At no point with in the next hour does the diaphragm switch (switch 1) move again with volts across micro switch terminals remaining at 240. Also at no point did the red float (A) rise high enough to activate the micro switch above it (switch 2).

I assume the circular molding is some kind of diaphragm that works on pressure as the water level rises, rotating the blue lever pushing out the plunger and activating the red micro switch and making the circuit.
A continuity test shows the switch to be closed with power able to pass thru it when the red micro switch button is depressed as the plunger moves out.
The circuit is broken when the plunger goes back in and the little red switch is deactivated.
Is this important, is it part of the problem or is it all working correctly.

I also put a test meter across the terminals on the heating element, and it read zero, it also read zero when the diaphragm switch was activated by hand.
No power, no heat, so no hot water, why!!!!!!!

Sorry if my post is a little long, but i really am at my wits end

Best regards,

Phil