  We point out that the ratio of $W^+ W^- \to W^+ W^-$ and $W^+W^- \to ZZ$
cross sections is a sensitive probe of the dynamics of electroweak symmetry
breaking, in the CM energy region $\sqrt {s_{\rm ww}^{}} \agt 1$~TeV where
vector boson scattering may well become strong. We suggest ways in which this
ratio can be extracted at a 1.5 TeV $e^+e^-$ linear collider, using $W^\pm,Z
\to jj$ hadronic decays and relying on dijet mass resolution to provide
statistical discrimination between $W^\pm$ and $Z$. $WW$ fusion processes
studied here are unique for exploring scalar resonances of mass about 1 TeV and
are complementary to studies via the direct channel $e^+ e^- \rightarrow
W^+W^-$ for the vector and non-resonant cases. With an integrated luminosity of
200 fb$^{-1}$, the signals obtained are statistically significant. Comparison
with a study of $e^-e^- \rightarrow \nu\nu W^-W^-$ process is made.
Enhancements of the signal rate from using a polarized electron beam, or at a 2
TeV $e^+e^-$ linear collider and possible higher energy $\mu^+\mu^-$ colliders,
are also presented.
