Jake_G wrote:After reading the rest of your reply, I am beginning to better understand your answer. Basically, post brewing, the solenoid chamber is flooded and water is help in place by the fact that the shower screen is "sealed" by the portafilter and spent puck. Upon switching to steam, the water in this space boils and gurgles out the tube. This makes perfect sense, but it's not something I've encountered first hand, which is odd. Maybe I just never noticed it?
The fact is that when the machine opens the 3way after brewing the discharge of pressure develops a flow fast enough to suck away quite a bit of moisture at the whole screen assembly together with the puck. So doing normal shots you might not have noticed it happening but if you were to play with the shot pressure opening the steam valve to simulate a dropping pressure and maybe go a bit too far, you are gonna end with less pressure in the portafilter at the end of the shot, less "suction" of the pressure discharging, a somewhat wetter puck and more moisture at the showerhead assembly. (you probably noticed that gushers also leave a wetter puck)
If you want to really exaggerate the whole thing you can turn on the machine letting go to temperature then lock the portafilter with an empty filter and flush it (like you would do if you were in a rush and were trying to warm up everything quickly). That way cant hold much pressure in the portafilter, the discharge tube can get wet but the shower screen assembly remains soaked, remove the portafilter and flip to steam, that water boils off fast and it looks almost like the whole thing is leaking for a second.
If you bring it to temperature and flush without the portafilter and then go to steam its mostly the shower screen boiling off because the discharge side is dry or barely wet.
Im sure that you wouldnt have much difficulties reproducing the whole thing, the hotter the system and more water is there to boil off suddenly instead of having the time to calmly drying up the more you see it... might be the routine OP uses that leads to it more often that usual.
Im travelling right now (more delayed than moving) otherwise I would get a video of it.
PS: I dont know how much the gurgling that OP hear is, he said sputtering which makes me think minimal and what I already saw on other Gaggias but if its an actual gurgling, kettle like, then yes he might have a leak. Without the machine in hand cant really exclude anything so who knows. In these threads it becomes a weird ping-pong of "try this""try that" to find some more leads and I always hope for folloups and an OP conclusion of the story to see what it actually was but most of the times we are left with the curiosity.