air leak only with collision gas turned on

I've recently replaced the N2 tank for my 7000C and when I autotune with collision and quenching gas I am now starting to see an air leak. N2 is about 50% and O2 is about 13%.  When I do just an autotune with the collision gas turned off, the leak goes away (still there, but very small, 4%:1%).  The GC has been without a Nitrogen tank hooked up for an unknown amount of time. I'm fairly sure that all of the fittings are snug, and there is a gas trap on the line. I would think it would take away the O2 reading if the leak came before the trap indicating the leak is post-trap. If i have a branch connection to a µECD that has its Make-up gas turned off, would that introduce a possible source of air? The last autotune was in 2019 and results were good but i'm not sure if there was collision gas turned on during it.  Any advice on how to figure out where this leak is coming from?  Thank you.

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