Furnace issues from previous visit likely caused from intake air allowing hot humid air into the furnace while it is moving cool air through the house and that temperature mixture is likely what caused the super bad rust issue and inducer to lock up. Advised homeowner possible remediation would be removing fresh air intake and instead pulling intake from basement to go around the condensation source. Homeowner is possibly interested in revisiting remediation plans come spring time. Could install stainless steel burners or could just change over to 1 pipe.