Completed tune-up on Goodman GMVM97 furnace. Tested igniter resistance (40Ω), verified inducer motor RPM (3450), inspected heat exchanger with borescope (no cracks), and measured gas pressure (3.4"WC). Cleaned flame sensor, restored 2.8μA signal. ECM blower motor performing at optimal CFM. System now operating at 96.5% AFUE with proper static pressure (0.4"WC).