  Longitudinal weak gauge boson scattering has been well known as a powerful
method to probe the underlying mechanism of the electroweak symmetry breaking
sector of the Standard Model. We point out that longitudinal weak gauge boson
scattering is also sensitive to the gauge sector when the non-Abelian trilinear
and quartic couplings of the Standard Model Z boson are modified due to the
general mixings with another Z' boson in the hidden sector and possibly with
the photon as well. In particular, these mixings can lead to a partially strong
scattering effect in the channels of W^\pm_L W^\pm_L \to W^\pm_L W^\pm_L and
W^\pm_L W^\mp_L \to W^\pm_L W^\mp_L which can be probed at the Large Hadron
Collider. We study this effect in a simple U(1) extension of the Standard Model
recently suggested in the literature that includes both the symmetry breaking
Higgs mechanism as well as the gauge invariant Stueckelberg mass terms for the
two Abelian groups. Other types of Z' models are also briefly discussed.
