Dishwasher works intermittently, then fills and drains but won't wash
My Kenmore 665.13693N411 dishwasher works fine for a week to a month at a time, then stops spraying. It fills and drains fine, and heats the water to steaming, but then it will run the entire cycle without spraying. During the wash part of the cycle I hear only a slight hum or whirr instead of the usual splashing sound.
The solution has been to run the diagnostic cycle: punch three buttons three times, wait for flashing lights, close door, wait 25 minutes for diagnostics to complete, then try a wash cycle again. One or two diagnostic cycles usually does the trick.
The error code displayed at the beginning of the diagnostic cycle is always F6-E4 = float switch open. But I hear the float switch click when I raise and lower the float valve, and the washer always fills and drains flawlessly, so I doubt the float valve switch is bad.
Nor do I think I have a bad door latch, because the washer will always run a wash or diagnostic cycle when I close the door.
I'm guessing my intermittent spraying problem is caused by an intermittently failing circulation pump, and that I should replace it.
Does that make sense? Is there anything else I should check first? Thanks!