The laser carriage on my S1 40w is suddenly difficult to move to the left and right, as when marking material position. It takes extra force to move it. It seems to overcome the resistance and move for a few centimeters, then resist again (as though something were off  with the motor pulley?)

I found the article on checking “Carriage falls off,” and followed its steps to the point that I have the carriage separated from the piece that connects to the belt. The carriage moves freely without any resistance or extra play. However, I am unable to move the connecting piece and thus the belt back-and-forth. 

This is with the machine completely disconnected from power, so I know that it's not a case of the stepper motor being powered up. The cable into the motor appears fine. There doesn't appear to be an easy way to get to the front of the motor where the pulley is connected,

When I look into the carriage at the belt, the rear side of the belt appears to be lower than the front side of the belt, as though something were out of alignment. How does one get in there to see if the belt is partially off the pulley, or tell if the stepper motor is somehow jammed?

Edit: The machine is only a few weeks old and the rails are clean and well lubed.

Second Edit: Looking into the carriage rail where the X-axis motor is attached, there's a possibility that one of the pulley set-screws is backed out enough to be rubbing on the hole in the rail where the pulley sticks up into the channel the belt rides in. Unfortunately, I can only see in with one eye at a time and don't have a super clear view. Anybody know of a reasonably simple way to remove the X stepper motor to get at the pulley to check?

Third Edit: XTool Support had me try some troubleshooting steps, and based on that, they're replacing the S1. Can't complain about that!