I have the home made setup and I found it difficult to keep centered. What I've been doing recently, though, is using a copper/brass or whatever it is fitting from the home made setup to hammer each cup in individually. I find that slowly tapping around the fitting in a circle gets the headset in quite easily and quickly, you just have to be careful to not jam it in lopsided, and for that reason to be careful initially until it's going in straight and you can hit it harder.