About that gurgle thing.
Assuming the head is screwed in tight, and the unit is does not have an air leak at the top of the tank, here are two ways to correct it.
For the occasional "gurgle", that is more apt to occur as the tank nears empty, take it off the mod and give it the ole thermometer shake to remove excess juice/condensation from the atty and or airway and out though the mouthpiece. A Q-Tip can also be pushed up the air way from the drip tip side if one is so inclined, but shake it out first.
If it is happening frequently, other than changing the head, just add some additional top wick. Doesn't have to be silica. Little bit of cotton on top of the stock wick will do.