Put a screw driver between the shiny brass flange ( cover) that is over the hard brass disk. it should pop off and show the screws.

My frigidaire unit had this problem a while back, traced it back to the instrument panel, it was shorting and stopping before the end of the cycle. It had other significant issues that pointed to it but not draining was the first indicator. Later on, it was not finishing cycles, starting without human input and then only the Heavy wash button would light up.

Got a used part off Ebay for 100 bucks because new parts were 8 months to a year out. ( mid pandemic).