You have to remove the rear brush assembly and that gives you access to install the anti-drain back flap.
this has been a huge issue for my Warrior SE. the rubber flap easily falls off when the bag is full, and it's a pain to reattach. Also each time after I pull the robot up for cleaning and put it back into the water, I later find the flap on the floor after a scheduled run. Had pentair come by, they sent a new flap, but it doesn't help. Seems like a design flaw, but I'm surprised that I don't see many reports about this issue, perhaps just a defect somewhere around the flap area. I'm tempted to permanently super glue the flap bumps to the robot wall holes where they attach (like 8 of 'em) but not sure if that'll work or ruin it.
you can stick the flap up from the bottom between the rear brush and the wall, line up the holes and pull the rubber bumps through the holes to attach it, without removing the brush.
This is what I did and the flapper kept coming off. When my new flapper arrived from Marina, I took the brush roller off to get a good look. I had to use a screwdriver to push the flapper in from one side and then needle nose pliers on the other side to get each rubber bump to fully attach. I think if I would done this with my old flapper, it would have stayed connected. You really have to get the bumps in there all the way, or it will keep falling off.
oh interesting!!! I used to just pull the bumps through the holes with my fingures they looked good but maybe that was the issue. I have now used plyer to pull them all the way in AND used hot glue gun as well, hopefully they stay this time for good! I already noticed the robot seem stronger with suction and wall claiming, but will see how it does. thanks a lot for sharing the tip!
