IPA does work to break up cured ink on UV heads, I have seen people use goo-gone as well without doing any damage to the head itself. however if you use a product like GG note that it will soften the built up ink on the heads, and you must use care when cleaning that off in order to avoid smearing the newly softened gunk into previously unclogged jets.
Anytime you make use of a solvent to do an agressive cleaning, after you let it sit on the head for a while, purge some ink out of the head before you try and wipe anything off, the fresh ink should help move the gunk out of harms way before you wipe it away.
Thee are a lot of solvents out there that will clean off cured ink, just be mindful that some of these solvents can also attack the epoxy or laminate that was used to assemble your printhead in the first place. A shiny nozzle plate will do you no good if it is laying on your shops floor...
