I tried a different grade of sandpaper, and it's SO much better. The first time I was afraid of sanding too deeply, so I used medium paper. Tonight I tried the coarser stuff and OMG what a difference. It's so awesome.
I will have more sanding to do; I need to get one of our big extension cords and use that to get the corners of the room. But it's definitely getting there. I love my Mouse so much.
I'm really happy my motivation came back. I'm not quite as driven as I was before, but I need to accept that I cannot go full steam all the time. It's okay for me to take a break; it does not equate to quitting.