Help diagnosing window problem!!

My driver's side window has just started jerking as it goes up and down. It studders all of the way down and does the same on the way up but will sometimes get stuck on the way up and I will have to pull it with my hand to help it get all of the way up. And once it is completely up I can mash the up on the switch and the motor will start grinding like it's missing or spinning freely. Is this the motor or the regulator, or something else? Please Help! I just replaced the motor with an Autozone motor about four months ago. What to do?

sounds like teeth are striped on motor or regulator need to pull motor and look at gear. if motor has all of its teeth it is regulator.