ok i think i need help from someone again

so I have two of these.
using the same juice and taking out the drip tip to start dripping...
the first unit would drip the juice all the way to the bottom section where the wick is
the second one wouldn't, it just stays on the top part that the drip tip connects to. it doesnt go down past the middle section with the spike. Any ideas why the juice isn't going down? I've tried looking to see if anything would be blocking the juice but I don't see anything blockages.