There isn't much plastic in this one.
The two peek insulators, and drip tip (also the 510 to 810 adapter if you happen to be using it) are the only things that could be actually burnt.
One of these pieces may have had burnt eliquid leech into them.
It's odd but can happen.
I would take it apart, then clean and dry the pieces separately that way you can get everything totally clean.
Once it's apart you will be able to figure out where the smell is coming from more easily.
Edit: soap and warm water will work good.