Regular peaks in baseline when heating column

Hi All, 

I am having an unresolved issue of ghost peaks and irregularities in my GC traces. I have tried bringing the column up above the final temperature and letting it sit with no injection. During this there are regular peaks in the bassline. These peaks fade as time goes on, but are still visible even after an hour at temperature. The bassline is also a bit noisy, fluctuating by about 0.5 pA after an hour. II replaced the septum. Haven't done any other maintenance but this column and inlet have not been used much since installed (maybe 20 runs total). Pictures of the traces are attached.

Some set up details:

Column: DB-1HT, 30m, 0.32 mm ID, 0.1 um film thickness

Cool on column inlet

Hydrogen carrier gas flowing at 1.6mL/min

Max program temp is 380. These images taken at 390.

Any help is much appreciated.

Zoomed out baseline showing temp ramp

Zoomed in once temp stabilized. See regular peaks.

Close in of bassline. Regular Peaks visible and very noisy.

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