One of my Duets is acting up, keep getting Suds errors F20, F35.  Checked the pressure hose and it is clear, perhaps made the mistake of blowing into the switch proper but seem to be non functional at this point.  Looked on line for a replacement, expected $15-$25ish, what do I see? $144!  Sorry no.  Will pull one from one of my other Duets and see if that remedies the issue. 

Machine is in need of new bearings and a seal, replaced them about 10 years ago. I may just junk it if parts are that expensive. I have another very nice Duet waiting in the wings, but I liked the Steam function on this machine, it has the steam tank above the tub. The other Duet I have has steam also, but I do not see a steam generator tank, they must have changed the design for this model, anyone know how the newer models steam function works?

It's a water level/pressure switch. Part # WPW10415587

Wow, had no idea.  Might be time to swap out Duets. If I come across the part at a reasonable price I might do the repair, otherwise it might get parted out.