Do the wipers function correctly when they are turned to the "ON" setting (constant wiping)?
I'm only suggesting this video as the car is fairly new to you and your wife. It shows the basic operation of the windshield wiper stalk.
407 851 8510 Sport Mazda Orlando Florida's Mazda Superstore - Mazda Sales, Parts, Service - 6239 South Orange Blossom Trail
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Now, assuming you're operating the stalk correctly, I would suggest spraying some electrical contact cleaner on the wiper stalk, then working all of the functions of the stalk to work the cleaner in and let it do its job.
If that doesn't work, you could try replacing the wiper stalk with a new one.
I don't think there is a fuse specific to the intermittent wiper function, but if there is, that would be the first thing I'd check. From what I could find, there is a front wiper fuse, but since the wipers appear to be working aside from the intermittent function, that fuse is probably ok.