Some gurgling is to be expected. The cartridge juice gets pulled into that metal mesh looking material, most of that material is out of sight, wrapped around the heating coil, but when you draw on it, the air gets pulled through the metal mesh, delivering air and juice to the heating coil to make vapor.
Three things cause you to end up with a mouthful of not-so-yummy juice; If the metal mesh is overfull, the lightest draw in the world will still just give you a drink, and even when working normally, the vapor works like steam, and condensates on the inside of the mouthpiece, eventually building up into droplets that you end up drinking. (the third is drawing too hard, which can cause the liquid to be pulled past the heating element faster than it can be heated)
For fluid control, take off the cartridge, and use a straightened out paper clip or something to push out the juice cup out of the mouthpiece. Use paper towel to wipe off the outside of the juice cup. Do the same for the inside of the mouthpiece.
Also wipe off the smooth metal exterior of the atomizer.
Without the mouthpiece on the unit (just the atomizer and battery), hold the e-cig with the battery led pointed at the floor. Take some short draws on the atomizer and see if your getting good vapor production. (don't inhale, just puff) (you could replace the the mouthpiece, but don't use a mouthpiece with a juice cup at this point)
If there is NO vapor, the atomizer may not be heating up. This is either due to the battery or a bad atomizer.
If there is vapor, the atomizer is working.
If the vapor is very light or almost non-existent and tastes like hot dry metal, then the metal mesh is dry and will need to be primed with e-juice.
If there was decent vapor, but it tasted like burning vegetable oil on a stove, then you've got storage lubricant in the atomizer. The most reliable way I know to get rid of it is keep loading it with ejuice and puff through it till the vapor drops off (best to not even inhale), then load it with more ejuice, and do it again, and again...after about 4 full battery charges worth of puffing, it should be pretty much clean. (just don't let it get too dry, add juice to keep it making good vapor)
Hopefully this technique will get the thing working normally. Also, when you replace the juice cup and begin to put the cartridge back on, try to line up the oval shaped juice cup, with the wire mesh in the atomizer so that the the mesh won't touch the sides of the juice cup.
I devised the above by working with some skanky tasting 901's that I got. They rock now.
I mostly use 801's (penstyle, ncig) now, but the principles are the same.
With practice you get pretty good working these things
Good luck!