To troubleshoot start at the wipers and disconnect the hoses and run the washers - if no water comes out, follow the hose to the next connection and unplug the hose there - repeat. keep going, back to the pump if necessary.

There may be a filter in the line, and a check valve - I had the check valve on one of our 740s turn to goo - perhaps from strong washer fluid.

If a check valve is bad, pop it open - there should be a small spring and a bit of thin rubber, DON'T lose the spring!

You can use a piece of dishwashing glove to replace the rubber - the piece is so small, your wife won't even notice.