For anyone who's got a new Dynasty laydown brush endbell version, the latest ones are coming out with thier brush hoods very very tight. I recently bought a motor like this from my LHS but it was not running correctly, so I took it back. We discovered the brush hoods were the problem and was causing issues with the motor as the brushes were getting stuck. The springs were not even strong enough to push the brush back onto the comm.
The fix was as simple as using a hood alignment tool to open the hoods up very slightly. Worth keeping in mind if you get a new laydown brush motor and have issues with it.