Unplug the Kenmore vacuum, and allow it to rest for two minutes.
Remove the exhaust filter cover on the back of the vacuum. The filter housing and cover sitson the back, toward the bottom of the unit, and has a label that reads "HEPA filter." Press the release tab and pull the cover outward to remove. You will now have access to the HEPA filter.
Remove the old filter by lifting it out of the unit. Discard the filter.
Install the 86889 HEPA filter into the vacuum with the airflow arrow printed on the filter pointing toward the cover. The foam seal on the filter should rest against the vacuum body.
Replace the HEPA filter cover. Insert the bottom tabs of the cover into the slots on the unit, and push the cover into place until it snaps signaling it's secured.