As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE, LEFT ENGINE ITT QUICKLY ROSE TO 860 AND SHARPLY DROPPED TO APPROX 820-830 SEVERAL TIMES. APPROX 10-15 BOUNCES IN A 10-15 SEC TIME. FL410, RAT -18, .90M. INSPECTED ALL THERMOCOUPLE CONNECTORS PER A23007C MM 77-21-10. APPLIED STABILANT 22 CONTACT ENHANCER TO ALL LEADS. PERFORMED TURBINE - INTERSTAGE THERMOCOUPLE TEST IAW AE3007C MM, ALL CHECKS GOOD. RAN A/C AT POP FOR 15 MIN LEFT ITT STAYED AT 780 DEGREES WITH NO FLUCTUATION.