Hi, it's Jim from Crucial Vacuum!
One of the main reasons most brush rollers begin to get jammed and eventually not turn would be due to a clog. Turn off the vacuum and flip it on its side. Is there any noticeable debris,such as hair or large carpet fibers? If you're looking to clean out your brush roll do the following. For the DC50 there should be a red button below the vacuum and just above the brush roll. Push this red button, this will allow the brush roller to be removed. On the brush roller itself you'll notice two more similar looking red switches. Flip these up allowing you to remove the top of the roller and gain access for cleaning. Clear out any debris and try rotating the brush roll once around to see what else may fall loose. Take note of how the bristles look too. Are they worn down and loose? If so it may be time to change your roller.
This handy video may further help in troubleshooting your Dyson.
Another item to check would be your vacuums belt. If this is loose as well it can affect your vacuums brush roll. Both are simple and easy fixes and can be done in just a few minutes.
Should you need any replacement parts for your Dyson in the future please feel free to order direct from Crucial Vacuum with free shipping and an exclusive 10% coupon for Fixya.com readers, use code: FIXYA10
Check out our lineup of Dyson replacement parts at the below link.
I hope this was helpful. If you would like further assistance, please feel free to give us a call at 877.750.9239. We have helpful and friendly customer care representatives on the line ready to assist you.
Crucial Vacuum Customer Care