The problem with using an old atty is the performance. Which can be an issue since you might think that there isn't enough juice in there. So, you squonk again and that leads to flooding. Another problem is if the coil/wick is gunked up.
That would make it so that it wouldn't hold as much juice as it would if it was clean (not by much of course). The flavor can also trick you in believing that it's dry. Which is usually marked with a kind of a burnt metallic flavor.
When I prime an atomizer before it's been used. I use 6 drops and let it sit in there for 10 minutes. The purpose of this is to let the mesh and wick get properly saturated.
Have you cleaned your atomizer lately? Also, how old is it exactly if you don't mind me asking?
Apologize for all the questions. It's my method of troubleshooting.