Have you tried rinsing the heads off, paper towel drying the dreadlocks and refilling? Slap it on the twist at 3.2v, the first few puffs will be sub par till it cooks the remaining water off. I've had some heads that have the odd burny plastic taste that cleared up once I washed everything out. As far as the ohms, I'd definitely check them with a multimeter/on-PV check; I've yet to get a Vision head actually meter to what it was labelled as (though they've always been higher).