As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 ENGINE TREND DATA SHOWS INCREASE IN EGT AND A DECREASE IN EGT HOT DAY MARGIN. ACFT GROUNDED. ACCOMPLISHED NR 1 ENGINE EGT SYSTEM INSPECTION, REF 77-21-01. FOUND S1 AND S4 OUT OF LIMITS IAW TABLE C. REPLACED EGT PROBES S1 AND S4 IAW 77-21-01. PERFORMED OPS TEST, REF 71-00-00. SYS CHECKS NORMAL.