Not sure if anyone else has come across this issue. We took off the analytical head for the first time to replace the metering seal. It was difficult to unscrew fixing screws especially the left one but they did come off eventually. The metering seal was replaced without incident but now we can't fix the analytical head back in place. The left hand side screw will not fix in place, almost like it is not long enough to hold the head in place. We did make sure that we ran the appropriate 'Change piston' function in the Agilent software beforehand so that the sampling unit was in the correct position before removal of the analytical head.
We have placed a service call for this problem but in the meantime I am wondering if I missed anything. I couldn't find any videos or guides how to do this other than the basic instructions so it seems to me as though it shouldn't be complicated