It is supposed to be loose in there but I suppose it could be locktited in if you want to. Otherwise, the procedure is to pre-assemble the packing nut, packings and sleeve onto the needle, running the sleeve on only a few threads. Now push the whole assembly into the hole and tighten the packing nut only enough to keep the sleeve from spinning, Then screw the needle all the way in until lightly seated, then back it out 1-1/2 turns. Finally, tighten the packing nut some more to secure the needle from spinning from vibration.