An apparatus in an example comprises a sheet holder, a separator surface, a feed head, and one or more arms. The method includes storing a manifold 32 that has a plurality of cleaning openings 42 in a configuration resembling that of the valves, in a position that allows clear visibility and access to the operation of the valves. The slides are positioned at angles with respect to horizontal such that the pull of gravity on the objects moving down each of the slides is greater than restraining electrostatic or frictional forces on the objects.