Performed B2 cleaning on gas furnace. Collector box is leaking from the bottom causing water buildup/rust on bottom shelf. Flame sensor has small crack down left side, after cleaning sensor is still worn. Recommend replacing both before further issues/non-ignition occurs. System is currently operating properly with marked issues. Passed carbon monoxide test at 0ppm. Ordered replacement collector box (non-stocked part) and flame sensor, homeowner scheduled for 1/4/23 830-9 arrival for replacement.