Unresolved Y-axis shifting

Seems prints are shifting in the Y axis. Looks like it loses some steps prints a few layers, then loses about the same number of steps in the other direction. Please see attached photo. Bottom is the bed side.

 

After loosening the Y belt tension, a lot, I ran another print that got all most all the way through without any shift. Unfortunately, it came loose of the bed before completion.

Since it was late, I put another print off and will make another attempt. Expect it should be fine.

On another note, I was also experiencing stringing but was already at the low end of temp for that filament. When I looked into the setting for minimum distance to trigger retraction, it was 200mm, almost 8 inches? Seemed a bit much, so set it to 30mm. No stringing, but it seemed to take almost 2 seconds to retract, and 2 seconds to extrude at each non printing move. Adds a lot to printing time over hundreds of layers. I guess I can look at some associated settings, probably retract distance, speed and longer minimum moves.