Gray tank valve

[Jim Keefer]

I have the 2005 mobile suite ck3. I am currently having a problem pulling the cable to open the valve on my gray tank. It has been getting harder each time I pull the valve. I have tried different items to clean it within the tank, have used Dawn, valve cleaners etc. to no avail. I was able to take apart and clean the black valve as it was accessible. I did follow the gray tank cable for a short Way and it seems to go forward towards the black tank and then under the blank tank? Now my question to you folks is, where is the black tank valve located so that I can repair, replace and or clean so that the cable pulls easier? Thanks in advance for your help!
Jim