If you have been using it, filling it, using it, filling it.......It could be:
1) Time for a New coil head
2) Flooded from Not cleaning/maintaining on occasion.
3) Coil head could have Loosened and is letting e-liquid leak past the seal.
4) Power set to low and Draw to strong, causing excessive Flooding. see 2 above
Remove Base with coil
Wipe coil with tissue/napkin/paper towel
remove Coil head
Wipe clean Base and Air Chamber below
Hold Coil head in paper towel and blow out
Insert coil head in base and secure snugly
Assemble and test again.