LG LDF8812 Diswasher - Self Cleaning Filter not cleaning itself

I have had this diswasher less then 9 months. It has worked well until rescently. Now is is leaving food and chalky residue on silveware, plates and glasses. We do not have a water softener, but we don't have very hard water (e.g. showerheads don't clog very fast.)
I removed the brown disk-like (filter?) unit from the inside bottom of this LG 8812 DW. (Approx. 12 screws.) I can hold it in my hand and look through the fabric-like screens on the top. I can see some debris inside. But I can't figure out how to open it to clean it out. There are no more screws to remove and when I try to pry it open with a screwdriver, I leave a mark but no sign of it popping open.
1.) Can anyone post a service manual for this DW? Hopefully, it will have an exploded view of the inside of this thing.
2.) Please advice how to open this "self cleaning" filter.