My three valve selector switches for the freshwater tanks are getting next to impossible to turn, likely they're just old! Has anyone replaced their plumbing and if so, what did you use? Also, is this the best location for them? Because I have a Marine mermaid heat pump, I have to take off the venting to get to the tanks. Not a big deal, but I thought there might be an easier spot, I was thinking of mounting them to the back of the galley large pullout drawer, accessible from the same settee locker. 

I'll have to check to see if they would still be below the water tank levels so that the water tank drains by gravity. Thanks for any suggestions or help. Take care, Rich.