Much more likely that it requires a darn good cleaning. There is little that can wear so badly that the brush will "die". The head assembly might split, but that's easily replaced once the proper part is in hand.
Remove the needle and the trigger mechanism (where the hose attaches), as it has an o-ring that will get destroyed otherwise, and soak in lacquer thinner. You can leave it in for half an hour, or longer. Then do a thorough cleaning with windex or simple green, and flush with distilled water, and you should be good to go.
If that doesn't work, send it to Badger (there are instructions on how to do so on their website) and they will give you an estimate to replace or rebuild. Sometimes they just require a tweaking to get back to factory new settings.