The invention relates to a method for evaluating the condition of a machine with a measuring point, which method is performed by a movable analysis apparatus. The solid catalytic system comprises titanium or vanadium compound, a compound of magnesium containing at least one halogen, a particulate porous support, and optionally an internal electron donor. A mechanism disables the power supply for a period of time during a start-up phase of reproduction so as to prevent transfer of residual marking particles from the dielectric support member to the transfer roller. The inventive device comprises at least one radially traversed catalyst bed. The slide frame is mounted in such a way as to automatically space each respective accessory a predetermined place with respect to the crop pickup device.