If all parts are there, the lift button spring may be weak and need to be replaced if the ejector claw is missing the rim, most good hardware stores have a selection of springs of similar diameter which could be cut to the right length. H&R won't convert an ejector to extractor, that's covered in the FAQs, requires machining the underlug to accept the extractor cam, you can do it yourself if you have a drill press or a mill.
Tim