A leveling assembly for setting a vertical prop is comprised of an inclined surface setting member 20 and a horizontal surface forming member 30. In a preferred embodiment of the invention, the preparation comprises a fruit acid, preferably citric acid, as acid component and for the improvement of storage-stability. The diversion valve is in the diversion fluid path and the controller automates the diversion valve position for the diversion valve unit based on a monitored wireline speed or a monitored wireline tension for a wireline unit. The retainer plate further has a push member extending beyond the end cap through a slot in the end cap. The side cover is substantially stationary with respect to the stationary part and is slidably guided in a guide rail.