if you need to quickly bump humidity, a wet kitchen sponge will do the trick!Thank you. I'm using my new cabinet. I did start spraying lightly with warm water when I open it. That helped the last two I think. Still quite a few pips.
as for needing another fan, I wondered the same thing in mine, (before the control unit went bonkers and melted the thing) I tied a small piece of tissue paper hanging from each of the trays, and realized I was getting a lot more air flow than I originally thought. Maybe you might want to move the control sensor down a shelf? I haven't seen the inside of your cabinet, so I can't say, but it seems to me that putting the heating element in the top is backwards as heat naturally rises....
and yes, definitely put a back on the trays! I'll suggest simple window screen or 1/4" hardware cloth.
Oh, and I was at DDS getting my DL renewed when my phone rang today.