The spike plate is a pain to remove and replace the first few times. I usually use a paper clip to slowly pry the plate out in order to efficiently clean the coil and atomizer.
Pull out the first bend on a large paper clip until its at a 90 degree angle. Get a set of pliers and bend the first 1/8 inch of the straitened end you started with at a 90 degree angle. This will give you a small hook to slowly rock and lift the needle plate out without damaging the coil or the wick. Once it's loose enough, it should fall right out, but don't force it too much.
After you get the plate out blow out the atty from the battery end and then soak both the atty and the wick in rubbing alcohol for 15 - 20 minutes. After soaking rinse them out in hot water from the faucet and blow out the atty again and dry the wick with a paper towel as well as possible. Screw the atty without the plate or wick onto your battery and dry burn in 3 second intervals until the entire coil glows all at once. Take the atty off one last time and blow it out again. Place the atty back on the battery then find an empty
tank cartridge and stick the plate and wick into it. Here's the tricky part; reseat the plate by firmly pressing the cartridge (with the plate still inserted) all the way in until the plate pops into place and the cartridge is fully inserted into the tube.
Like I mentioned earlier, the first few time will likely be a pain. If you wiggle the cartridge a little it sometimes helps to seat the plate easier. Remember to use firm and steady pressure but don't force it too much because you could destroy your cartridge and kill the atty. It's a little scary the first few times, but you'll get a feel for it over time. If you need any more help or need me to explain anything further let me know!