Sorry about that, the server has been glitchy lately and I couldn't connect.
Are these used carts or blanks? It sounds like these maybe used carts, 20 drops in either should not lead to any flooding as long as your are dripping on the side of the carto housing and holding the carto at an angle. Gurgling or flooding at 20 drops, let alone 23 drops sounds like the pfill material has been compromised and you have a burnt cart.
So let me state a few indirect things on this issue. Sometimes if an atomizer is flooded it can be woken up so-to-speak by placing the carto on a Passthrough which will quickly vape off the flooding due to the higher voltage.
Check your battery, take a flashlight and look at your battery connector, is there a black ring around the post accompanied by black gunk in the outer threads. If so, this is an indication that you've been leaking juice onto the battery connector. This is quite common and a drawback of using the Condom method of refilling as residual juice runs down the air tube and stays on the carto threads causing a black build up on the battery threads.
To clean your battery, take a toothpick and run it around the post ring until it you can see metal again. This should remove a black/green gunk like substance, then take a needle and run it around the air intake holes which feed into the outer ring of the post. Using a little alcohol or vodka will make this task simpler.
A dirty battery will have a large effect on vapor production, draw, and flavor.
Sorry, I keep getting disconnected to the server....
Anyways, you said you have syringe, I have something for you to try on a blank carto if you have one but I will wait for your response and see if your battery needs cleaning and what type of carts, used or blanks your are using.