wobbles, have you ever measured your mandrel? The odds are slim but with cartridges being so close together, maybe you have another mandrel in your die.
My guess is either something is sticking (collet not moving, slots in collet not cut/clogged), or brass is rock hard.
I use the Challenger press with my collet dies and on occasion do put enough pressure to move the press A BIT. You need some force, but not enough to become superman.
There are always more traditional dies to go to if this one is too complicated.
Jerry