The alternate valve is in the bottom of the machine roughly in the
middle (turn it on it's side and pop off the plastic bottom plate). I
removed the valve - that required taking off two hoses and unplugging
the connector. The valve seems to have leaked a bit and had gunk all
over it. I took it apart and cleaned it (there are some plastic gear
wheels and a motor that pops off). There is a micro switch which
detects the rotation of the valve. The switch is a 'normally closed'
type and wasn't working. I removed it and carefully eased it apart and
cleaned the contacts. Put it all back together and now the dishwasher
is working again!