Top load washer not cleaning clothes properly

I have a high efficiency Whirlpool Cabrio top load washer that is not cleaning clothes correctly. Model # WTW5640XW3. Everything appears to be working properly, but obviously something is amiss. I’ve checked the lines (in and out, no blockages), cleaned the machine and detergent tray thoroughly, checked the drain system. I’m thinking that the agitator might not be working as well as it’s supposed to, but it’s only a guess. I know the agitator is working, as clothes are moving around, but maybe not to the full degree it is supposed to. Online help has been difficult to find, normally I can find and fix issues. Not this time. Any suggestions are appreciated!!