Using light finger pressure, carefully push the black plastic tabs off the white plastic hooks.

Remove the black plastic bracket out through the front of the heater housing.

Remove the two Phillips #2 12mm screws and remove the clear window from the black plastic bracket.

If the buttons were sticking, clean the black plastic bracket in warm soapy water and allow to dry.

If the clear window was dirty, clean it in warm soapy water and allow to dry.