Abstract: A method and apparatus for cleaning residual toner from the surface of an imaging member in an electrographic imaging system which uses carrier means to transport toner by triboelectric forces to develop an electrostatic image on the imaging member. The pre-clean corona current is adjusted periodically during the lifetime of the carrier as necessary substantially to neutralize the charge on residual toner so that it may readily be removed by a rotating cleaning brush having substantially no charge thereon. Adjustment is in response to a periodically sensed aging characteristic, the charge density of the toner, such as at successive preselected operating time intervals representing increments of carrier useful lifetime. In this manner, cleaning efficiency is maintained.