I bought my own Christmas Present Christmas of 2022. I've been running my Roomba 9s for almost 2 years at this point. My home floors are 95% hard surface, either tile or hardwood. I've replaced only the wiper and pickup rollers, nothing else. Typical problems are what many users report; gets stuck on shoelaces, small mats, eats objects it cannot digest, etc. For my part, human modification, sort of like what I have to do with my dishwasher, pre-wash everything. Roomba is no different, one must go around the house making Roomba safe to operate correctly. My spouse has exceedingly long thick hair, combined with both a short haired dog with incredibly thick fur beneath, and a long haired Colley, this is the reason for most of my replaced parts.For 15 months Roomba was very consistent, and I learned what to do in order to look at my iPhone from wherever and get the "job successfully completed" message. However, strange behavior began to happen. Roomba would find unmapped territory that was not there, abort jobs, send itself to be emptied and not return to finishing the rest of the job, when asked to do a certain mapped area in the house, do another area, wonder around apparently unaware of where it should go or do next.Then the behavior got even more strange, it would turn itself on, without a directive at any time of the day, and finish a job it had started but not been able to finish (not a charging issue), have a spontaneous start, leave home only to return a minute later.And then, one day Roomba just stopped and shut itself off. The app said it was doing its job but clearly it was not. pressing the home button did not get it to return home. using the reboot option in the app yielded briefly blinking bin lid light. Removing the battery for half an hour followed by reboot seemed to get Roomba to wake up but the effect just did not last and eventually Roomba was found lifeless is some corner, unresponsive again.Perhaps some other Roomba owners have noticed small dust and dirt particles gathering beneath the glass/plastic lens cover on the forward facing camera just aft of the bin cover. I have since realized; this is a flaw in the design. cleaning behind this lens cover is not an easy thing to do. In fact, it is not a thing most people would attempt as it require disassembly of all major components save for the vacuum motor/blower, after which the two plastic body pieces which make up the bulk of the body cavity must be separated. There are screws which must be removed for this operation. However, most of the attachement of these two parts are one-way plastic clips, integral to the two parts. It is simply blind faith that in separating these parts you will not end up with an expensive bag full of parts which cannot be reassembled.Once these two main body plastic part have been separated, the lens cover can be cleaned or removed. I removed this lens cover and now use Roomba without it. Roomba has worked flawlessly for two months of cleanings (approximately 20 jobs.) All strange and weird behavior is now missing. Back is the Roomba I had initially purchased. I believe Roomba 9s uses this camera for a significant part of its sensor protocol in cleaning. My 9s became unresponsive is phases, as the lens became more obscured by small dust and hair particles with time. Having the camera/lens cover totally sealed would have solved this issue. Perhaps iRobot solved this problem in later issues of the same model, not on the one I bought.