I've got a problem with a 311 where it keeps stopping short of floor level, then levelling in, only in the down direction. I've replaced dz, dz1 and dz2,the PIB in the the drive and also the tacho. Now i've tried to do a learn run but once it levels into the bottom landing to begin, the tool reads out "no learn error" and also reads UP "DZ2". Has anyone had this before?