An apparatus for facilitating removal and installation of mold insert members of a mold assembly from and into the clamp unit of an injection molding machine comprising a material distributing sub-assembly from which at least one material distributing nozzle projects, the apparatus comprises a two-part frame comprising an ejector part, an injection part being releasably connectable to the material distributing sub-assembly, and support pins spanning between the ejector part and the injection part when the injection part is separated from the material distributing sub-assembly, and guide elements projecting from the material distributing sub-assembly to engage a mold insert member received in the injection part and effective to align that mold insert member relative to the material distributing sub-assembly. The two-part frame comprises first clearance bores and second clearance bores allowing protrusion into the mold insert member of, respectively, the material distributing nozzles and the guide elements.