Repaired a Generac Guardian 22kW whole home generator today. Diagnosed faulty voltage regulator using Fluke 87V multimeter. Replaced with new Generac 0G8442A111 AVR. Changed oil using Mobil 1 5W-30 synthetic and installed new Generac 070185E oil filter. Replaced spark plugs with NGK BPR6ES. Cleaned carburetor using CRC carb cleaner. Adjusted governor spring tension. Tested battery with Midtronics capacitance tester. Performed load bank test using ASCO 1340 portable load bank. Verified proper voltage output and frequency. Updated firmware using GenLink software. Completed repair in 4 hours, restoring reliable backup power.