What you have is most likely a hot spot, which is pretty common on a Protank but really hard to diagnose. Usually what happens is that the nice wick and coil that you just setup will get compressed when you put on the center post. You'll then create a hotspot where there were no indications of one before. I found all this out the hard way over 6 or 7 coil rebuilds.
The easiest way to tell is to remove the top post and the flavor wick and then burn the coil with some juice on the wick while blowing on it. If a portion of the coil starts glowing while the rest stay dark, you know you've got a hotspot. And again, I do this after I've done a full reassembly so that I can tell whether installing center post has deformed the coil.
With a Protank, the learning curve is really finding out how to build a tight coil that won't deform when you put the center post back in. From experience, now I use a 1mm or 1.5mm silica wick and wrap the coil tightly using half of a wooden Q-tip. The 1.5mm wick threads in fairly easily and the coil is small enough that it should be ok with a 1.5mm or even 3mm flavor wick on top.
The easiest way to tell is to remove the top post and the flavor wick and then burn the coil with some juice on the wick while blowing on it. If a portion of the coil starts glowing while the rest stay dark, you know you've got a hotspot. And again, I do this after I've done a full reassembly so that I can tell whether installing center post has deformed the coil.
With a Protank, the learning curve is really finding out how to build a tight coil that won't deform when you put the center post back in. From experience, now I use a 1mm or 1.5mm silica wick and wrap the coil tightly using half of a wooden Q-tip. The 1.5mm wick threads in fairly easily and the coil is small enough that it should be ok with a 1.5mm or even 3mm flavor wick on top.