A sample of 3.79 × 106ψ(2S) events is used to study the decays of charmonium to axial-vector plus pseudoscalar mesons. The branching fraction for the decay ψ(2S) → b±1(1235)π∓ agrees with expectations based on scaling the corresponding J/ψ branching fraction. Flavor-SU(3)-violating K1(1270)- K1(1400) asymmetries with opposite character for ψ(2S) and J/ψ decays are observed. This contrasting behavior cannot be accommodated by adjustments of the singlet-triplet mixing angle. © 1999 The American Physical Society.