Replacement of pump seals, pistons and check valves has been described in the 193_0010S - LC110S user manual and 193_0021S - LC 110S pump head maintenance. In addition, this tutorial contains YouTube movies that show the procedure in more detail. Before using this material read the instructions and warnings in the user manual. There is also a video instruction how to set the torque tool for the LC 110S. The movies in this tutorial are on YouTube.
Exploded view (click to enlarge):