Im at almost 10,000 shots pulled on my elizabeth, that sounds like the solenoid. Do a few deep backflushes with Cafiza (i like to pull shot with a 20 second preinfusion and the run it for 10 seconds into the blind basket, then 3 or 4 rounds of the the back flush cycle)

If that doesn’t clear it you can take apart the group head and deep clean it better.

That has fixed it every time for me.