I'm trying to replace the flush valve gasket in a Kohler Rialto toilet. I was able to get the old gasket off relatively easy.But I'm having a hard time turning the plastic piece (not sure what to call it-flapper assembly/flush valve?) with the new gasket.I can't get any leverage and I don't want to break it using channel lock pliers.It only needs about an eighth turn but I'm not getting anywhere.Any tips would be appreciated.