I too was having a difficult time with auto leveling no matter which print head I used. I noticed that the print head was not making contact with the corner washers. It came very close but was not making sufficient contact. I searched for a software solution to make the head move one mm more and could not find a parameter that I could tweek.
So my solution was to remove the soft plastic corners and put a #2 stainless steel washer under it to lift the entire surface up by about 0.4mm. That worked great and I can now reliably print.
Would still like to know if there is a software parameter that would effect this.