In my playing around with the T3/T3S heads I have discovered something that I think might contribute to the gurgling.
When I pull the air tube off and look at the top two (flavor) wicks they have been pushed to the side in the center forming an area open to the coil. Sort of like if you were to place two strings side by side then take the ends and push them together each string would bend out opposite to the other forming an opening between them.
If I take my tweezers and turn the wicks over so they are laying one on top of the other instead of side by side the gurgling problem goes away.
I don't know how this opening is created. It might be the way I clean them. I put the contact end in a modified syringe (see images below) and force water
through it first out the air tube then I plug the air tube and force water out the wicks. This might contribute to spreading the two wicks apart. YMMV

