I have gotten fed up with ruined prints because of bed and or gantry drift. Over time will will publish more about how to get around this problem. As it seems to be a fairly common problem with the CR10-S5 in particular. I found that between prints my gantry could fluctuate +-4mm which makes it impossible to level the bed through the interface. If you put these blocks under the gantry on both sides and make sure that both sides rest on the blocks you will eliminate the issue as a temp solution. ultimately adding a belt between the 2 z-motors will resolve the issue. these blocks will be useful for getting that belt setup properly.
Additionally. I added some wings that can be adjusted to help quickly check to make sure that your bed is level. I will be adding a clip to the back side that would hold the wings in place and allow for measurements to be made to help with leveling too.
This is a work in progress.