I too have gravity feeding problems with my PW900. Seems the primers don't want to flow and drop into the rail. Only lube that prevents stiction is silicon spray. And the primers only partially enter the window to get to the primer ram. Seems like it gets hung up on the alum. Sometimes the primer catches the wire on the ram. I check this every time I place a wad and nudge the primers through the window. My primer slide looks less elaborate than yours though as maybe you got the second generation PW900. Mine is first generation.