Not sure if it's still relevant, but I had the same issue.
Bed would not move smoothly, would hardly move at all..
Turned out to be to much tension on the belt. Not sure how that came to be after about a year..
But anyway, at the front in the middle you see the belt loop around, there are 2 screws you can undo slightly and move the bracket a bit to loosen the tension on the belt.
This fixed it for me, and it's easy to do, you don't even have to remove the bed for this.
Many good reply here:
The belt pulls in one direction only. This means the bearings will wear in that direction. Eventually, The rotor will start rubbing against the stater. Without the tension of the belt on the shaft, the magnetic field may equalize, And center the rotor. By rotating the motor 180°, you will position the rotor on a good portion of the bearing, This will get you going for a little while. But it is not a fix. you will need to replace the motor.
Note: the X and Y motors move approximately the same, But in different directions. This means they will have a similar bearing problem. Plan on replacing both of them.
Also note: make sure you check the idler pulley on both axes, replace as necessary.
Thanks for the replies on this
Yeah sounds like the stepper has gone to Phuket. If you do replace it, maybe take the opportunity to open up the failed motor and see if it's something fixable. No risk of it's redundant.
It is more than likely 608z or 608zz bearings in the motor. I keep one spare motor on hand and change it out when one goes bad. I then rebuild the old one. It costs me only a couple of bucks to rebuild.
Replace the motors and then rebuild the old ones. While you are at it, replace the idler bearings and the belts, check the remaining bearings for travel, and perform a complete tune-up.
My Anet A8 eats idler bearings for breakfast and the bearings in the motors for lunch. What you are describing sounds a lot like a bearing that has gone.
Loosen the eccentric nuts under the bed slightly until it moves freely. The rollers will get flat spots if they sit long enough but they will round back out with a little back and forth. Probably not the stepper. I have seen this with new 3D printers and very used ones.
Let me know if that helps,
sounds like the bed wheels need to be adjusted, i had a similar issue on mine and found a flat spot on one of the wheels that was causing the issue