To unflood : hoping that you haven't filled the tank to the brim, and that you can turn the tank upside down and have the two holes in the bottom of the centre post clear of the e-liquid and in air. If not, drain a bit out of the tank with a syringe. (If you skip making sure those holes aren't submerged you will never ever get the flood cleared)
1. Turn the AGR+ upside down.
2, Put the drip-tip to your lips (tank still upside down) and blow.
3. The flood will clear, and excess liquid will come out of the air-holes between the tank base and the locking ring. You'll need a tissue round that bit.
4. Repeat until the liquid clears.
5. Turn the AGR+ the right way up. Take a primer draw (unpowered). If it gurgles, repeat this entire process.
To avoid this happening in future, filling the tank properly is key. Only use the fill-hole. use a real needle filler or syringe and be mindful that if you block the entire fill-hole, air will be unable to escape and the carto will flood again. Fill slowly.
Another angle to approach is to be mindful of how many holes you punch in the cartomizer and how deep the holes you make are. (ignore me if you use pre-punched or slotted cartos). If you punch your own, stop turning as soon as you hear the carto pop. Use two holes.
Another consideration is that if you punch the cartomizer too close to it's 510 connector (the battery end) it deforms the circular shape of the carto. If you did it too low, you break the seal between the eliquid in the tank and the 510 connection, because the deformation might be causing the O-ring located at the bottom section to be unable to make a seal. To avoid this, when assembling, screw the centre post into the bottom section, insert an unpunched cartomizer and screw the locking ring on. With a marker pen or sharpie, mark through the center post holes. Take the cartomizer out and punch your holes where the pen marks are.
Another thing to consider is to make sure that all the tank sections are screwed down tight, and that more critically the O-rings are there. The tank works on air pressure to constantly feed the carto with eliquid. If you remove the top-cap to refill you break the air-pressure system and your cartomizer will flood (unless you replace the top cap REAL slow and careful with the fill-hole scew out). If you fill wth the fill-hole but don't let the air escape the air pressure will force eliquid into the cartomizer which will flood it.
Hope it helps