Recently I noticed a larger pressure fluctuation during the injection process for my 1220 autosampler. I tested the system using Lab Advisor's Pressure too High test and it failed stating that there is a clog. I switched out the needle, needle capillary, and the needle seat, but the issue is still persisting with a fluctuation of 15bar during the injection process. I believe the issue is during the mainpass-bypass switch.
Are there any actions I make take to reduce this fluctuation or is this okay? I am running water and methanol as my mobile phase.