AnyCubic Chiron shifting in Y axis I have an AnyCubic Chiron, and sometimes the bed doesn't move correctly.  This causes the prints to shift and ruins the print.

I've spent a lot of time watching it, and noticed that when this happens, the belt stops moving for a short period of time, and then a "thunk" and it continues printing, with the slight from when the bed wasn't moving.

I've captured a video that demonstrates this.  You can see it get stuck about 22 seconds into the video.


                
            

It's a new machine, and printed fine for the first 5 or so prints, and then this problem started happening.  Now almost every print fails.

Things I've checked:


Belt tension seems fine.
Belt is not slipping.
The bed moves smoothly back and forth, no binding, nothing in the way.
When it's failing, it doesn't seem to be because the head is stuck on the print.
The screws attaching the pulley to the shaft are tight.
The same G-code file that used to print successfully now fails, and not in the same spot every time. Doesn't seem to be related to what I'm printing.


I'm not sure where to go from here.  Is this a bad stepper?
AnyCubic Support suggested I swap two of the motor drivers (X and Y) and after I did that, the problem disappeared.  I've had a half dozen good prints in a row now, no problems at all.

The drivers are inside the computer module - had to flip over the printer, take off the cover and pry out the top two modules and put them back in swapped.  Not difficult, but probably worth getting advice from AnyCubic before going ahead and doing it yourself unless you're comfortable with this sort of thing.