I just spit right back.
Welcome.
Seriously, I've got the Tron S tanks, not the Cubis, but what I do when a tank is spitting is first cross my fingers and hope it's just because it's been left and the juice has over accumulated on the wire coil. In other words it will clear up once it's vaped on for a bit. Next I'll try blowing through the atty while firing it (try not to do this to a point of burning the wick so 2 shorter blows may be better than 1 long one). I'll then recheck my power setting as sometimes by turning up the power the spitting will be reduced or eliminated. On a build-your-own there are some other things you can do too but with premade atomizers I can't think of much else except putting a bit of screening underneath the drip tip to block the spits, some atty's come with screening in place.
I never considered putting a piece of screen in there but it sounds like a mighty fine idea to me - - worth a try at least.
The Cubis design is somewhat flawed in my opinion - it has a top airflow and a very narrow chimney, too narrow to get a q-tip down (even cheap dollar store cotton swabs will not fit). I found the coil heats up fast and the chimney fills with warm thin liquid and there's no way to get it out - you need to let it sit and drain back and it just takes to long do that because, hey, you need to vape after all. I've tried .5, .6 and 1.0 ohm coils and all seemed to get hot pretty quickly.
When I quit smoking and started vaping all I had was that Cubis style AIO that Joyetech makes. I didn't realize I needed a back up (and back ups for my back up) so while I was waiting for a new set up to arrive I used to drive around in my car with the air conditioning blasting while holding the AIO up to the vents to keep it cool. LOL It did help but yeah, can't be driving around all day just to vape
I retired that unit because I finally got some back ups but I've had to pull it back out and start using it again because one of the back ups is acting up already (only 2 weeks old). I'm using 1.0 ohm coils and it is fairing a bit better for me as 1. the ambient air temperature has cooled off a lot since August and 2. I have another set up and alternate between the two so I am not chain vaping on just the AIO.