An apparatus for targeting a desired target site on a body tissue that separates a first body cavity from a second body cavity of a patient includes a catheter having a longitudinally extending catheter lumen and adapted to provide access to the first body cavity. A first passage is defined in both a crankcase and a cylinder head to connect an interior of the crankcase to a valve rocker cover chamber defined by the cylinder head. The scheme can be applied to every possible configuration of an insertion device, and is therefore also suitable for use in so-called free electron lasers and other light sources based on particle accelerators. The drive screw interfaces and connects with the plunger carrier. The receptacle includes a porous bottom and flared upstanding sides.