Dirt Detect Light blinking constantly - Pippy

All right, you can see the video here, from start to finish on this problem that started AFTER I cleaned the gear box out. Pippy was not doing this before, but she needed the gear box totally cleaned out and re-lubed. Which I did--took almost an hour. There was dust in the motor too, which I cleared out with canned air and tweezers.

Put her all back together and started her up, and here is the result. Dirt detect light will appear soon after starting even though the floor is actually really clean; then after a minute or so it will blink constantly while she goes about cleaning for the rest of the time.

If it's not one thing, it's another! I will keep you posted about how I fix this.