Unplug the power cord from the electrical outlet. Turn off the gas supply to the dryer.
Lift the lint screen from the top of the dryer. Remove the screws next to the lint screen compartment.
Insert the putty knife between the top panel and front panel. Press the knife into the internal clips three inches from each front corner. Lift the top panel up and back to rest against the wall.
Remove the two screws holding the front panel to the dryer cabinet. Disconnect the door switch electrical connector from its harness.
Lift the front panel up to disconnect it from the dryer base. Set the panel aside.
Remove the screw holding the flame sensor from the side of the burner funnel. The burner assembly is on the left side of the dryer cabinet.
Disconnect the two wires plugged into the flame sensor. Lift the flame sensor out of the dryer.
Position the new flame sensor inside the dryer. Install the two screws that hold it to the burner funnel. Plug the electrical wires into their sockets.
Reverse the dryer cabinet disassembly steps to put the Whirlpool dryer back together.