I had a great talk from one of the factory guys week before last and was really excited to take my new rig out and use it for a week, i left all tanks closed to tell how long we could use it before we had to drain just as a good base line, and made it all week with no problem. As i was un-hooking and draining tanks i got all of them i thought but found the aft grey tank didnt drain, the coach was level and i tried it again, nothing came out, my guage is reading 2/3 full and if i am on a hill it is slightly less or more depending on which way i move, is the tank actually full or not? I dont really know how else to check it other than with the guage and now i have to leave to drive to idaho from alabama and dont have time to deal with it. The coach is at Camping World of Dothan Alabama getting a 2nd A/C and Washer/Dryer installed right now but i dont know if I should pay them to look at it or not, any help on what i need to do to check this would be greatly appreciated.