Hello. I have an Agilent 6890 GCMS. It has been a LONG time since I've had to do my own maintenance so looking for advice. The GC-MS instrument is on but needs a columns change/septa/liner/etc but can someone remind me what I need to do to prepare the instrument for changing all of these parts? For example, some GCMS instruments don't need to be shut down and can reduce injection port/column oven/transfer line temperatures. What about flow and is there any other "quirk" of this system I should be aware of before taking on the task? Thanks in advance.