Cleaned & checked condensing gas furnace. Inspected heat exchanger & flue venting. cleaned burners & flame sensor. Checked voltage & amp draw of motors. Test capacitor. Replaced air filter. Blower: 5.5A. Inducer: 1.75A . Gas pressure: 3.4 inches water column. Customer has gravity boiler that leaks flue gasses at warped upper access doors. Suggestions: boiler is a potential CO hazard. Recommend replacing boiler.