As others have noted, get rid of the green foam thing. Pull it out, make sure all vestiges of it are gone. Those things can introduce mold and ruin every stick in there.
I've had varying degrees of success with the salt test. My recommendation would be to buy the Boveda calibration kit. It's only $5 or $6 on Amazon and considering the overall value of the cigars you will have in there, that's a cheap price to pay. When I finally bought the calibration kit, it turned out that my calibration from the salt test was off by about 7%. That's pretty major. So, yeah, step one is to really make sure that you have the proper humidifying device and a properly calibrated hygrometer. Otherwise you'll be chasing the Rh all over the place this Winter.
I've been using the KL for almost a year now and have had to no issues - it's holding the Rh pretty steady. This Summer, it never went above 67% and over last Winter, never dropped below 63%.
If you do go with Boveda packs (and I think that's a great way to go, FWIW), get 2 or 3. Having more than one will not over-humidify your humidor but, at some point, they will need to be recharged (and that can take up to 2-3 days - especially in Winter). So, if you only have one pack, then your humidor won't have anything keeping the Rh stable while you recharge the pack. If you have a couple, you can always have at least one in there at any given time.
But, again, to start, remove the green foam and any evidence that it was ever in there and buy the Boveda calibration kit if you want to be sure. Once you know that your humidor is dialed in and the Rh is pretty steady, you'll find that you don't even check the hygrometer that often since you can trust the environment inside.
Cheers