I have just had to remove the hotend assembly which meant disturbing the IR sensor etc. After roughly levelling the bed in relation to the X-Carriage rods I decided to work through printer commissioning again to get everything adjusted as per the WiKi original build procedure... http://wiki.e3d-online.com/wiki/Printer_Commissioning This involves homing the print heads moving the IR sensor about (for dual) and moving the Z-axis up to the nozzles. Several things didn't happen.. Using the front panel the X axis moved up to within say a cm of the nozzles but the carriage didn't move to the centre of the bed "After homing has completed the Printhead will stop in the middle of the build space. " Ignoring this after a further couple of attempts to "home" I proceeded to follow the instructions to move the bed upwards to touch the nozzle(s) The bed moved up but only until on screen the reading for Z was 000.0 (logical) but would not move up any further, using the front panel control. This was about 5 or 6 mm from the nozzles. Octoprint was running (on screen message on BB) but I wasn't logged in. I logged in and was able to move the bed up using "home" but had to power off as the bed wasn't going to stop. ------------------------ Although I'm following the build instructions commissioning instructions (as I'm not aware of any post build calibration instructions) it seems that there must be extra steps needed to reset information (stored in the Rumba ?or in Octoprint?) before re-running calibration.