I still don't have a solution to the Drake smearing but I now have a better undersatnding of the problem.
Sometimes post flush fecal smears are left on the throat of the Drake and sometimes not. I've determined that they are left when the pile of preflush excrement is large enough to stick up a few inches above the water line (think ice berg).
I believe it is the weight of the above-water-line portion of the pile that presses the below-water-line portion of the pile against the sides of the below-water-line throat of the Drake.
Smaller volume bms that stay below-water-line or float do not leave fecal smears.
This observation may explain why some Drake owners have the problem and others don't.
Does this match the experience of you who are having the below-water-line smearing/staining problem with the Drake?
This observation does not apply to above-water-line splatter that remains after flushing. I believe that is simply a result of not having a full bowl wash toilet.
Sometimes post flush fecal smears are left on the throat of the Drake and sometimes not. I've determined that they are left when the pile of preflush excrement is large enough to stick up a few inches above the water line (think ice berg).
I believe it is the weight of the above-water-line portion of the pile that presses the below-water-line portion of the pile against the sides of the below-water-line throat of the Drake.
Smaller volume bms that stay below-water-line or float do not leave fecal smears.
This observation may explain why some Drake owners have the problem and others don't.
Does this match the experience of you who are having the below-water-line smearing/staining problem with the Drake?
This observation does not apply to above-water-line splatter that remains after flushing. I believe that is simply a result of not having a full bowl wash toilet.