Last fall, I had same issue with grey tank valve on my 2016 Micro Minnie 1706FB. Ultimately, the control cable was just corroded up preventing movement of the internal cable. And then when I was pushing to try and close it, I bent the handle rod, making the situation worse. I was able to re-bend the rod and spray some WD-40 Specialist Dry Lube into the end of the cable by the handle and worked the handle until it moved enough to close. I just buttoned it up and winterized it leaving it as a summer project. Over the winter I contacted Winnebago Customer Service with my year, model and VIN asking for specs. They e-mailed me a dozen or more of prints for all the water, frame, floorplan, electrical and sanitation systems. I responded back asking for manufacturer name and manufacturer PN for the 1 1/2-inch grey and 3-inch black valves which they provided. The LeSalle Bristol valve PN's are supplied with the 72-inch control cables already attached. Rather than replace the full grey valve and connected control cable, I just ordered a new 72-inch generic cable from Amazon for replacement (dumb me trying to save a few bucks). I have been working on this project for the past couple of days. The underbelly will need to be cut open to gain access but be careful as there are multiple wires for taillights just laying underneath. I am still working on this project as it's not just a simple control cable swap as one would think with a LeSalle Bristol grey valve. This has been a big PITA! Whoever designed this dump valve/control cable system should have their engineering degree revoked and sent back to school and learn that "design for disassembly" is a real thing!! This thing is put together like a multi-layer puzzle. To get to the set screw for cable removal required full removal of the valve (a long hour Odessey of not being able to get the clamping screws out as they hit the grey tank - too long and needed to be sawed short), disassembly of multiple holding clips and three set screws to get the cable finally removed. All taking multiple hours. If I had it all to do over again, I would have just replaced the full control cable/valve assembly and not mess with the cable replacement. Ultimately, if you are remotely handy and don't mind laying on your back for multiple hours, it can be done. I would envision this being at least a $500-$700 job for a tech to perform the repair.
