Andy,

There is a trouble shooting and a diagnostics section in your manual so
check the code for correctness et c. If it's more complicated than that you
may need to call a service man for help. Your water softener is not listed
on GE's web site.
I think your sensor senses a couple of magnets held on a turbine that
spins when water flows. So, if I'm correct about the sensor, it is most
likely a problem with the main PC board. The motor and switch you mention
rotate the parts that control the amount of time spent on each step of the
regeneration process. They are working ok.

Dave M.