Here's how I did it.
My watermaker membrane housing and clark pump was located under the boards of the aft bed. To remove the clark pump, I closed the sea water intake and removed the two low pressure hoses and the two high pressure hoses. Then removed the four screws holding the mounting plate and then the clark pump can be removed.
Make sure all O rings are in place before presenting the cylinder up and reapplying the four allen head bolts. Repeat for the other side.