I picked up a 6 pack of hygrometers from Mr Bezos for under $11 shipped. Could be had for a little less on fleabay, but would have to wait considerably longer with shipping from China. Anyway, 1 of the 6 was way off just getting them out of the box. I did not want to send back the whole lot. So, I took out the 2 LR44 batteries, and I was able to get the back off. It is held in my plastic clips. The battery holder comes out and then you are able to access the board. The board slips out of the front housing. You can leave the LCD in the front housing. You can see the board pic that in the lower right corner there are pins for RT and RH for temp and humidity. There was some solder globbed between the RT and RH pin. I simply scrapped off the excess solder and reassembled. Works great now and is verified via salt test to be within +/- 3%.

Later had to do another one.

I would venture to guess that many non-adjustable digital hygrometers are very similar in manufacturer. It seemed totally worth it to open it up and see what was going on. Also, after reading much suggestions, I have put stickers on the hygrometers to let me know how far off they are.

https://m.imgur.com/a/PYQf9zO 

Back in the day I used to worry about the accuracy of my hygrometers but then took the advice of “...just get some Heartfelt beads or Boveda packs and forget about it...” and never looked back.

Ya, I am cheap and have unscented silica litter.

Izon uses a litter box ?