Originally Posted by shilala

That's step one of diagnosing your humi. You absolutely have to salt test your hygrometer. Doesn't matter if you just did it last week, it's absolutely critical.

I'm not sure when the dollar bill test came into being, but it really says absolutely nothing about whether the humi leaks or not. If you want to see all the places she's leaking, fill her up with distilled water and turn her over. You'll see exactly how bad she leaks and where.
At that point you can seal the glass with silicone and add some foam weather stripping and a latch and test it again.
If you can get the old girl water-tight, she's going to be air-tight. Period.
Good Luck, my man!!!