  We give improved estimates for the non-perturbative parameters appearing in
the heavy quark expansion for inclusive decays. While the parameters appearing
in low orders of this expansion can be extracted from data, the number of
parameters in higher orders proliferates strongly, making a determination of
these parameters from data impossible. Thus, one has to rely on theoretical
estimates which may be obtained from an insertion of intermediate states. In
this paper we refine this method and attempt to estimate the uncertainties of
this approach.
