That was my problem with my first drying attempt, in a toaster oven w/ a fan. Problem was the closed door, high or low temp still had the issue.
Just got my first batch out of the FA brass dryer (pretty sure it's a relabeled Nesco food dehydrator, although there's slight differences in the handle design). Totally different - look brand freaking new on the outside. Inside is 'meh', but who cares. That part doesn't touch most of my dies or the case gauge.