Customer noted water at indoor furnace and wet filter. Checked system and found a crack in the main plate that separates the heat exchanger from the unit. Condensate leaks through this crack and down assembly to the filter. During operation, the gas valve coil is noisy which may cause failure to valve. Completed replacement of heat exchanger on furnace. During removal found 2 additional cracks in Trane furnace that was causing some poor flame patterns. Completed replacement of gas valve that was operating noisy. Checked gas line with bubble soap. Tested gas pressures. Operated system from customers thermostat.