Diane, this can be caused by dirty or defective bumper sensor as well as dirty cliff sensors. Clean the Roomba with compressed air and "slap" the front bumper. Apparently, the front bumper mechanism can get stuck with any contact with a wall etc. which will make the Roomba back up. Use [http://www.ifixit.com/Device/iRobot_Roomba_4100#guideList|these guides] to work on your Roomba. Hope this helps, good luck.
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Diane, this can be caused by dirty or defective bumper sensor as well as dirty cliff sensors. Clean the Roomba with compressed air and "slap" the front bumper. Apparently, the front bumper mechanism can get stuck with any contact with a wall etc. which will make the Roomba back up. Use [http://www.ifixit.com/Device/iRobot_Roomba_4100#guideList|these guides] to work on your Roomba. Check [http://www.robotreviews.com/chat/viewtopic.php?f=1&t=11389|on here] for more information as well. Hope this helps, good luck.
Diane, this can be caused by dirty or defective bumper sensor as well as dirty cliff sensors. Clean the Roomba with compressed air and "slap" the front bumper. Apparently, the front bumper mechanism can get stuck with any contact with a wall etc. which will make the Roomba back up. Use [http://www.ifixit.com/Device/iRobot_Roomba_4100#guideList|these guides] to work on your Roomba. Hope this helps, good luck.