I didn't know where to post this, but I guess a new topic is fine.
My male gouldian has had minor scaly face mites for a while now (a bit of unevenness on the upper bill near the nostrils). I applied Vaseline/petroleum jelly to his beak twice and almost all of it has cleared up. Petroleum jelly is safe if gotten in the mucous membranes or consumed in small amounts; avoid clogging the bird's nostrils with it and all should be good. A thin layer is adequate to suffocate the mites.