Check the thread on the push-in tubing fitting that screws into the solenoid. If the thread is parallel, it shouldn't have PTFE tape, and the chances are it has a seal, possibly at the bottom, to mate with a corresponding surface in the solenoid. If the fiting thread is tapered, and the female thread in the solenoid is, too, then it's a PTFE tape sela jobbie. Or could it be one of these, with an o-ring seal: