I thought I had fixed this problem, but I found the root cause of my issue with the X-axis losing steps. The X-axis is binding at each end, causing it to lose step when it’s brought to the X limits.
I made a video illustrating the issue and note that the X Stepper motor was removed during testing, as you can see from this photo.
Thank you, William. I could not find the PDF, but I found the video, which provided guidance about adjusting the bolts attaching the Z carriage to the linear bearing at several points along the axis, and this fixed the binding issue. The machine is back together and upon jogging the x axis to the both ends it no longer binds.