DC25 brush not staying on more than 10 seconds. If you turn the machine off then back on the brush turns on for 10 seconds again and so on and on! Please help is it a reset? I tried the brush motor direct to wall and it works fine, this makes me think a switch is bad and heating up and turning off. If you can tell me what you think I can fix it I just don't have testing equipment to run it down. Thanks!