Spectra water maker fresh water flush module valve position

[Portage_bay]

I'm getting ready to start up a long pickled yet new to me Spectra Newport 400. PO left the flush water flush module valve in "OFF". The manual I have says nothing about where this valve should be to start and run. "RUN" or "SERVICE" are the labeled options.

I've called Spectra, they are not answering calls.

I've changed all the filters.