Resolving high frequency noise in FID baseline and significant temperature ramp with temperature

System: The GC is an 8890 with TCD in series of two FIDs in parallel (switched via valve). FID 1 has methanizer while FID 2 doesn't.

Had to put the system on standby for 3 weeks over Christmas so kept carrier flowing through the system with all heated zones turned off. When I came back to the lab and ran a blank, I noticed FID 2 has some weird high frequency noise and the baseline ramps pretty badly with the oven ramp. FID 1 is fine.

Baking the detector didn't resolve the issue so just wondering if anyone had some suggestions?

The below screenshots are of the blank runs with temp ramp. The middle panel of each is FID 2.

Before Christmas (15/12/2020)

After Christmas (14/01/2021). Also some low frequency noise that occurs about half way through the run?

High frequency noise when zoomed in on the baseline


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