As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT 3651, WHILE HOLDING AT 240 SO. OF STL LT OUTER DEICE VALVE C/B TRIPPED PART WAY THROUGH CYCLE. AIR RETURN TO MEM. MAINTENANCE SWAPPED VALVES P/N HTE250076-1 HH11 AND HH5 C/B MX3 AND F26 P/N MS3320-3. OPS CHECK GOOD. SWAPPED, PERFORMED IAW AMM CHAP 30.