I have a plugged needle on a hitachi L-2200 autosampler. The ferrule (i.e. needle sleeve) that is used to secure the needle (and keep it from leaking) to the needle guide fits extremely tightly. I can't get a new sleeve onto a new needle. With great difficultly, I was able to the old ferrule off the old needle, but now I can't get that one on the new needle (or back onto the old needle)! Does anyone know a trick for this?