Just bought a 2014 Bighorn 3875FB, and can't get the front black tank to dump. Been full timing for 4+ yrs, so am familiar with the dumping process. The spec sheets and owners manual all say that I have two Grey, but only one black tank. But I have 4 cable pulls for 4 valves (not happy about these cable pulls, compared to what I had on my Southwind). I've attached pics of my setup, please advise!!