I’ve occasionally had this issue where I’m jogging up the Y-axis with the game controller, on the fastest speed, and it’s like it hits a ghost wall with just the left stepper motor. I can’t tell if the left stepper is grinding-to-a-halt, or if the left stepper is simply stopping, and it’s causing the right to make that grinding-to-a-hault sound.
I’m tempted to think some debris has gotten past the sweeper on the ball screw and it jammed it up and brought it to a halt, but the sweeper looks good and tight, and there’s not a lot of debris/chips on the ball screw. When it happens, the right stepper just keeps pulling, for the half sec it takes me to release the controller. I then back it towards home for a few inches, and then tentatively creep it back forward away from home, and it will proceed all the way to the end. However, when it gets to the end, the right gantry will arrive before the left. Equally, if I jog it all the way forward towards home, the left gantry will arrive at zero before the right. There’s a noticeable gap on the side that’s late.
If I re-home it, it will correct itself.