the model, the pole structure of the heavy quark propagator prevents solution of the meson BSE. This is clearly a shortcoming of the approximations involved. In ref. [@DL97] the heavy quark DSE is examined from the point of view of the gauge technique. This is essentially an improvement on the rainbow approximation to the quark-gluon vertex which is designed to respect the Ward-Takahashi identity. An alternative approach, and one which we follow in this paper, is to replace the bare vertex Ansatz with the Ball-Chiu vertex Ansatz [@BC80]. We shall see that in the heavy fermion limit the gauge technique and the Ball-Chiu vertex are equivalent.

Regarding the gluon propagator, our treatment differs from ref. [@DL97] in that it is principally numerical, enabling us to concentrate on a more realistic class of model gluon propagators. Specifically we study the simple gaussian Ansatz employed in ref. [@BL97], designed to model the infrared enhanced behaviour of the gluon propagator, and a model proposed by Frank and Roberts (FR) [@FR96] which includes both an enhanced infrared behaviour and the known asymptotic ultraviolet behaviour. In order to deal with the FR propagator, it has been necessary to formulate a properly renormalised version of the 