Dionex ASE 200 pump issue

I have a ASE 200 that has been idle for a long time in excess of 6 years. I brought the unit up and initially had it working. Unfortunately I was extracting a polymer that condensed in the lines. Now that I have the lines clear and the valves swapped when I rinse the unit it performs the rinse completes the rinse then the arm pulls back. Solvent is still coming out of the unit, if I kill the power to the pump it will stop so I do not believe that it is a back pressure issue. Any suggestions would be great.

Equipment: Dionex ASE 200