My Roomba 560 seemed shy as it was backed into a corner with a dead battery every time I came home. So, as I had done many times before, I cleaned all the LED sensors under the bumper and fitted a new battery. No change. I eventually found this site about the nine beep dance of death. Ah, more dust in the sensors, I thought. Testing showed the faulty right bumper switch. Taking it apart I was pleasantly surprised by the use of optical rather than mechanical switches. Still, dust could still be a problem. I cleaned it all out and reassembled. It worked for one more day.
Perhaps the emitter and receiver were not facing each other. While playing with these bare components on their circuit board I noticed the other bumper switch seemed to activate. So a faulty IR emitter was a real possibility.
I found both parts for sale in the UK for 68p. But postage was £12! Eventually ordered from SparkFun and waited a couple of weeks. Just a few dollars to fix after all that. Can't believe I had to order those tiny parts from the USA though.