Thanks for all your help CK. After reassembly the conditioner is taken fine. But it still overflowed! So then I removed the trap (first time round I cleaned it in-situ). I cleaned the trap thoroughly and even immersed it in Caustic Soda for 24 hours. After it was replaced still had the same overflowing. My guess is that the fault is in the control mechanism, not the pressure sensing side of things. I presume that I have to remove the dial (as before) and remove a bit more until the controller is free from the chassis? Are controllers too difficult to repair, ie should I look for a second hand one? Know any good sites to look?

Connor, March 2013

Yes, I did use a bottle brush, and blow and suck to ensure that air flowed as it should (I did that first time around). I have found a simple answer to the problem; use a different wash cycle from the one I habitually used. The overflow only happens with one of the cycles (G). That also suggests to me that it is the controller at fault. But now I have a working solution I'm not going to spend any more time on it; I've spent longer on it than the machine is worth already. But thanks for your help.

Connor, March 2013

did you stick your finger or something like a bottle brush up in to the clear air chamber bit and make sure it was free of gunk?
got me baffled now!!

CK, March 2013

these are so easy to sort as a rule???
do you see the water going up and up above the door glass then start to pour out?.As the pressure increases it gets to a level and then switches water off.If however the pressure drops it will try to refill until the pressure is back to the cutoff point.pull the black pressure hose off and suck air out with your finger on the other end.now see if it holds a vacuum for a good length of time using your tongue as a stopper if that makes sense.Taking the pressure switch apart might not of done it any favours and if that is leaking will cause your problem.NEVER in all my time have I had an issue with the timer causing an overfilling situation on this model machine.blocked vent tubes on top of the tub also cause water to pour out soap draw

CK, March 2013

Extra detail. The machine does not overflow after the initial intake of water, only overflows during the additional intake partway through the cycle.

Connor., March 2013