Auto home x-axis failure - normal operation x-axis fine

Vertex 3D Printer Vertex - Issues while printing
1

I have a very strange issue. Last week I finished the k8400 with 2 nozzles.
I did several prints this week… worked fine, but suddenly it “broke” with 2 issues :

The auto-home function does not retract the x-axis to utmost right position (y-axis retracts normal), it does not move to the right at all. Instead it moves slightly to the left and stops.
When i use the x-axis controls from the front panel, they work correctly moving left and right.

Now i push the x-axis to the right manually (gently) and start printing.
The printing works fine at first, but after 1 or 2 hours the x-axis starts shifting.

What I have already tried without any change:

  • Switching the driver boards
  • Tuned the belts
  • Oiling the rods
  • unplugging/plugging in the x-axis cable on both ends
  • Made sure there are no disconnected cables

I have firmware 1.1 for 2 heads (the one that was factory loaded).
I used 1 filament in “single head” setting in repetier, sliced with curaengine.

The strange behaviour of the auto-home worries me. I have not found any topic that describes this.

I wonder if both problems are related?

2

I fixed the auto-home by cleaning the stop sensor.

The shifting was also gone with my next print, but I reorented theobject in a position more to the right and with less width in the x-axis. So I’m not sure it’s gone, I will investigate further.