Well there are just as many types of spray paint as regular paint and the thinners will be dependent on the type of paint in the rattle can...
But, since the stuff is now dry try this stuff it will remove most paints, and you can pick up a gallon at Wal-Mart for under $10 in the automotive section...
Castrol Super Clean
Fill a bucket or pan up with this stuff and then drop the part in for several hours or overnight, the paint will fall off, you can use a soft brush to remove any hard areas, then soak in several baths of clean clear water for a few hours... Make sure it's rinsed very well prior to repainting.
You can also drop the part in a ziplock bag and fill the bag with a few cups of the Super Clean and remove all the air in the bag forcing the liquid around the part, that is if you want to conserve the stuff...