Dear Ursula,
Thank you for bringing up these issues. I've made the following fixes:
1) I've now changed the file labelit/interface.py so it no longer checks mosflm versions higher than 7.1.0, rather it just assumes everything will work. You were probably using ipmosflm 7.1.3 so that's OK.
2) I've changed the file cctbx_projects/iotbx/detectors/context/config_detectors.py so that serial_number 926 is now recognized as a Beamline 8.3.1 detector, with the correct beam center convention, which is different than many other beam lines.
These changes will go into the next nightly build of PHENIX. I do not know when SBGRID will roll out the latest bleeding edge, so if you or the sysadm would like like to patch the old code I'm attaching the needed files here.
Nick