Performed heater tune-up on a Rheem two stage heat pump system. Checked the electrical, mechanical and performance systems of the unit. Cleared, cleaned, flushed and treated the drain line and cleaned the exterior of the air handler. I did find one of the air handler breakers at the main panel had failed and was not sending proper voltage to power up the electric heat strips. Repair options were presented to the homeowner and she chose to have the breaker replaced. I replaced the breaker and cycled power at the thermostat. Verified all heat strips are now operating. All UV lights and surge protection devices are working as well. No other major issues were found. The system is operational at this time.