As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CRUISE FLIGHT, FL210 WITH CABIN PRESSURE SET IN AUTO. CABIN RATE INDICATOR NEEDLE PEGGED ITSELF OFF THE SCALE IN A CLIMB UNTIL CABIN PRESSURE WAS 10,000 FT. AFTER SEVERAL CLIMBS/ DESCENT OSCILLATIONS AND EMERGENCY DESCENT INDICATED PROBLEM CORRECTED IN CONTROLLED DESCENT AT FL 180. INSPECTED PRESSURE SYSTEM, PRESSURIZED AIRCRAFT TO 7 PSI. SYSTEM CHECKS GOOD ON GROUND AT THIS TIME. REPLACED ELECTRIC CONTROLLER.