Taz 3 y axis skipping steps?

I believe I’m getting skipped steps on my Y-axis. My prints come out with area’s shifted 1-2mm to one direction on the y axis. Consistent all the way up with spacing anywhere from 5-15mm between shifts. The shifted print area only last for about 5-10 layers and then it shifts back. I will upload pictures tonight. I think the problem might be my servo’s overheating? I’m running the medium abs auto support slic3r settings from lulzbots site with a few adjustments that would not affect this like a wider brim .

Here’s my analysis so far.
-first noticed on large prints with large infill area’s (1hr plus times and sizes larger than 60mm area’s)
-small objects less than 40mm by 40mm and print times of under 40 minutes or so are fine

What I’ve done to mitigate the problem at the moment
-slowed any speeds in slicer to be no faster than 105. The only 2 speeds that were faster are nonprint moves(150) and nonsolid layer infill(115).

Slowing the speeds has completely stopped this from happening but has added a lot of extra time to my prints. I’m pretty sure the infill speed of 115 was fine but the movement speed of 150 was the problem. I haven’t tried to isolate it any further yet but I just wonder if anyone else has had this problem. Like I said tonight Ill put up pictures of the prints and also hit the servos with my IR thermometer. Is my thinking right or is it something else?

How tight does the belt feel on the y axis? Use this method to guage: http://www.simplyrecipes.com/recipes/the_finger_test_to_check_the_doneness_of_meat/ (a bit odd, but it works!) Somewhere around medium-well is tight enough.

Check the belt pulley on the Y axis stepper motor. It should be firmly secured onto the stepper motor shaft using the set screw. The belt shouldn’t rub on anything but should be centered within the pulley and idler belt path.

Skinny object

Big object

My belt tension is about medium well I think. It only has about half inch of play if that when I push down on it.
Servo temps

I’ve seen something similar to this happen when the pulley is too far down on the stepper motor shaft and is rubbing on the “face” of the motor.

Turn the motors off and slowly push the bed back and forth. It should move along the rods smoothly. If there is too much resistance, then that could be causing the issue.

Good call, after I looked and followed the sounds I found this for my y motor. The pulley has slide down on the shaft, rubbed my belt down a little bit. You can see the build up of rubber shavings. I cleaned them up and slid it back up the collar, problem fixed.