I was experiencing ghost peaks in my water blank shots so I decided to do some maintenance. This included a new S/SL liner and septum, removing the first inch or two of the column, FID disassembly and ultrasonic cleaning of the jet, and reassembly. Now I have a different issue. At rest, my signal decreases periodically, then returns to zero, only to decrease again. See picture.
Any ideas what could be causing this new issue?