The i9+ worked great for the first week I had it, then the problem started. It would stop after about 10 seconds of starting a new run and give me an error message saying the rollers were jammed and needed to be cleaned. I checked the rollers many times over and there was no hair or other debris in them at all, but every time I would start a new run it would do the same thing! I called irobot and they told me they would send out a new cleaning head unit. It seeemed like they had been down this road before. After a week the unit and I installed it as per the istructions and it has worked great to date. Keeping my fingers crossed it does not happen again! I do love this thing and I hope it last a long time