My k40 play with me. I rebooted, reinstalled all drivers still the same. Somtimes do half job and then go to a side. Like on video. Any ideas ???
Thats a tough one…I cannot really tell too much from the video…maybe loose belts?
Or maybe in the set up? Hopefully someone else will reply too.
Belt cleaning did help 
Ohh good!
Double check the model and serial numbers in the software. Mine was wrong but the machine worked fine for a little while then it just started doing everything at about 5mm per second. Fixed the numbers and it’s been working fine since.
Sorted. The problem was some dirts on the belt