Abstract: A platform is held atop a vertically moveable dual position leveling base by three draw screws, three push screws, and three spring-loaded pins. The leveling base is configured to secure and orient the platform such that an upper surface of the platform is substantially horizontal with allowance for adjustments in each of two positions. The platform is pushed upwardly relative to the base by the spring-loaded pins. The orientation of the platform in one position is adjusted by the three draw screws, which pull the platform down against the upward force of the spring-loaded pins. The base also has an upper position in which the platform is pressed into sealing engagement with a lower mating surface of a chamber. Three adjustable push screws provide the desired platform orientation by limiting the movement of the platform towards the base.