Swigert: "Okay, Houston, we've had a problem here."
Lousma: "This is Houston. Say again, please."
Lovell: "Uh, Houston, we've had a problem."
Lovell: "We've had a MAIN B BUS UNDERVOLT."
Lousma: "Roger, MAIN B UNDERVOLT."
Lousma: "Okay, stand by, Thirteen, we're looking at it."