greenturtle36 wrote:... It's soaking in vinegar as we speak.
Considering all the tank soaking and shaking effort you have endured I thought you might like to have a look-see inside the waste chamber to actually see those bloody waste-full sensor electrodes, what they look like and where they are located. If you do, then click this link: http://gsplews.lkgnet.com/gsp/Scooba/4. ... tm#%C2%A72
, followed by looking & reading.
P.S.: If I were faced with a soiled tank such as you have been dealing with, I would leave out the vinegar and try diluted sodium hypochlorite solution (i.e., dilute to strongest household use concentration given on the bleach bottle).
If you decide to try this solution here's a hint (which I have not tried): I think less than two measuring cups of solution could be effective, but you would have to rig some way of supporting the tank at a steep angle to make the reduced amount of solution totally envelope the entire lengths of those two sensor rods for the soaking period.
I would first experiment with plain water to determine the holding orientation that accomplishes rod wetting, but does not drain water (solution later) out of any intake duct.