DW618 ROUTER

I own a dw618 plunge router. It is about 5 yrs old but I've only used it once. About a week ago I was using it when the magnet ring shattered into a million pieces. I replaced the magnet ring but now the router won't work. When I turn it on and try to spin the armature manually, the motor attempts to turn for a second, then stops. Anybody know what could be wrong now?