Dont hit the button until youve salt-tested ALREADY. Then see what your reading is, adjust dial as necessary till it reads 75, THEN hit the button.
I try to do this right through the ziplog bag I use for testing. I then leave the hygro in there for another 24 hours to check if the calibration is correct.
Also remember the salt test should be done at room temp. Ive done it in my cool basement and its thrown the calibration off.
But as I said before, change the battery FIRST so you wont have to just repeat this step in a month.
This is what all 5 of my hygros look like
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"One fart can foul the air for everyone" - Esteemed philosopher
"If avoiding the nasty $hit is being a snob, them I am guilty as charged."- Same esteemed philosopher.