camping world link did not work......Just purchased trailer. Has been sitting in a park for the past three years. Thinking of moving, and just trying to get things in order. Just read Papa-t's post and thought I better respond.
Once you get them rinsed out thourghly they may stop leaking, if not add about a 1/4+\- cup of cooking oil to the empty tank, you'll be surprised how much that helps to lube the seals.
As for cleaning, I just use a good healthy squirt of the el cheapo dishwashing soap or laundry detergent from the dollar store & sloshing it around with a couple gallons of water in the tank while traveling seems to work for me & it also lubricates the valve seals.