Lifting control mechanism

Help with mechanical design - initially an order for three hours work to help generate a concept. Ideally I would like to discuss the ideas through we bex or similar to help us fully understand the requirement. A mechanism is required to lift and lower a pair of steel rollers onto a surface. The rollers are 180mm diameter x 80mm wide. The rollers weigh about 6KG each. The rollers will be mounted approximately 1000mm apart. In the down position the rollers are 150mm beneath a containment box. in the up position the rollers must be at least 50mm off the surface. In the up position the rollers must be effectively locked such that they cannot accidentally come into contact with the surface. The rollers are attached to arms that must be pivoted as shown in the drawing. So it is the arms that must be acted upon to generate the downforce required. The rollers must be independently sprung against the surface with a force of up to 500N. I would like something that can be operated by hand from each side of the containment box.