How to Flush Si-Tex Autopilot?

Last month my Hynautic helm unit began to leak fluid. I pulled the helm and had it re-sealed. While I was at it I replaced a line and drained all the old fluid from the system however there is a Si-tex autopilot attached which has old fluid in the lines and pump. Is there some way I can flush the old fluid from the autopilot before hooking everything back up and filling with new fluid? The manual I found only covers filling / purging a newly installed system.

Thanks,

Ryan