The bearings (not sure of the correct term. Agate?) are not located symmetrically. While the one nearest the user is sitting flush in its recess, the opposite bearing is not.
I think this is most likely the problem. The agates have to be level (with respect to the scale body) for the beam knife edges to be supported properly.
If one is higher than the other, it will definitely make the assembly work worse than it was designed.
It could be as simple as cleaning / reassembly. (Once you get the right tools.)
But if it is a genuine manufacturing error, RCBS owes you a new scale.