Hi,
Just tilt the washer back and prop it up with some wood blocks. Three screws are right on the front at the very bottom. Use a 9/32 socket to remove them. The front cover slides right off. The drain trap cleanout is right in the middle. Turn the large white knob counter-clockwise to remove it and clean.

Thank you !!

The F35 indicates that the main control board detects a problem with the analog pressure sensor (water level pressure switch) in the washer. This component senses and controls water level in the washer. This failure could be caused by a pinched or broken air hose between the air trap at the bottom of the washer tub and the analog pressure sensor. It can also be caused by a clogged air trap or a failed analog pressure sensor. If you are able to unplug the washer and pull off the top panel, you can check for the probable cause of this failure.

To remove the top panel, remove the screws on the very back of the panel that secure it to the washer cabinet. Pull the top panel back slightly and then and off of the washer. It is on the side wall just behind the expansion control board. You can check the air pressure hose connection and the wire harness connection on this component.

This component costs around $99.This information was based on the general description of the washer model that you provided (Kenmore Elite front load washer). There are several different models of this washer.