UPDATE:
Rubbing alcohol does work, with plenty of elbow grease, but it works a lot better if you run the dryer on hot for a few minutes before you try. Warning: this produces even more fumes than alcohol-on-cold-metal. DH also lightly scrubbed with a plastic scrubber using alcohol, and this really got a lot out. Make sure you follow with a hot dryer/paper towel or rag wipe, though, as it leaves a lot of residue.
HTHS.
*****
A pen blew up in our dryer - somehow it was left in a pair of jeans. I'm just about crying.
Any suggestions for cleaning it out?