Haas face-frame cabinets

I have Haas face-frame cabinets, the drawers of which are fitted with Grass epoxy slides with little wheels. The fixed rails are not attached with brackets. The inner ends fit into oval holes in a rail at the back of the cabinet. The outer ends are held by a screw driver through the rail of slide into an insert set into a hole drilled into the edge of the face frame. The rails are 22.5" long overall. I need only the little insert, about .25" dia. but will buy the entire slide if I have to. Color of slide is almond. Help!