I took the hoses off of the pump and found a beat up guitar pick lodged in the intake of the pump.
Here's what's strange: No one has played the guitar in my house since before we bought this washing machine over 5 years ago. No one in the house claims to have had a guitar pick in their pocket for as long as they can remember.
Here's what's even stranger: The French student we have staying at our house (but who has not done any laundry yet) said "Oh, I play the guitar." So my daughter pulled out her old guitar, tuned it up and our international guest is in the living room strumming away with the mystery pick!