A Reactor for solid phase synthesis comprises a vessel, a plurality of filters arranged in the vessel and a plurality of filtrate outlets for evacuating the filtrate out of the filters. One of the plurality of projectors is arranged spatially in substantially a plane symmetric relationship with another of the plurality of projectors so that the images are projected at projectors angles onto the screen to be substantially in alignment on the screen. The method generally includes the steps of removing the stakes from an aperture on a driveshaft, removing an original bearing assembly from the aperture, inserting the replacement bearing assembly into the aperture, inserting the spacer into the aperture and retaining the spacer and replacement bearing assembly within the aperture with the retention assembly.