The Arterial line was checked for air, none was found. The alarm could not be cleared. The bubble detector was moved to a different point along the tubing and the alarm could still not be cleared. The bubble alarm was turned off and on twice without resolution. Hand cranking took place while a colleague was called to assist. Colleague switched off the alarm, moved the pump from hand crank back into the motor and successfully went back on bypass. The bubble alarm was turned back on after about 5 minutes when the patient was stable. No more issues.