As reported in 34677, the wandering bump in the ST2 Corner2 CPS Spectra showed again.  First seen at this location in June 2016, it was gone after a site power outage. A couple weeks ago, test suggested its origins were inside the vacuum system, 34820.  I speculated other in-vacuum sensors might be the perpetrators.

Today, with the ISI offline, I sequentially powered down and powered back up the Corner2 GS13s, the L4Cs, and then the T240.  The bump while steadily wandering around, remained proudly above background until the T240 was off.  So far it has not returned.

See the attached plots for the Sensor signals for time line and the CPS Spectra (note T0 time.)

I will update and close FRS 7576.