It took me a while to get mine working well. It would also jam up after it dropped down - just sitting cockeyed on the primer tube. I gave that filler tube a very small chamfer on the inner diameter and it's worked great since. I actually started using my Dillon primer tubes directly, rather than filling the tube that came with my Vibra Prime and transferring the primers to the primer tubes.
Also, for some reason, Dominion primers tend to be a little sticky feeding in to the primer tubes, so I tap the bottom of the fill tube occasionally as it's vibrating and it feeds just fine. I don't have to do this with CCI or Federal primers.