I don't know how close it is to fitting, but sometimes you have to get a little drift or something and tap on the snap ring to get it into the groove. It's just really tight sometimes. You should be able to see if the top is really seated, though.
Again, if you want to work on it but the shop is closed or whatever, the loaner ball joint presses will let you take it out and inspect the bore, etc. and put it back together. I can't remember which order, but I think the lower gets done with the upper out so there's room for the tool to come through the upper hole. Same thing for tapping them in with a large socket, hammer and drift. It helps to route your tools through the upper hole for pounding the lower ball joint.