I have a Craftsman router model 315.174321 that will not run, I can lock bit, and then release and router will start but runs for just a few seconds then stops. any ideas as to what may be causing this problem?
The only real maintenance you can perform on a power tool like that is to keep it clean and replace the brushes from time to time. There should be a brush that unscrews from each side of the motor's housing.
If that isn't the problem, I doubt that the router is worth what they'd charge you to fix it.
I second that!
When it does run look at the cap screws where the brushes are located and See if there is a lot of sparking where the brush makes contact with the armature. if so Un plug the tool and remove cap screws and pull out the brushes. clean out with compressed air. inspect brushes for ware and replace if need be. reinstall and start the tool.