Sm Hydra issues

[688sonarmen]

I recently bought a Montague humidor, 3lbs of heartfelt beads and a sm Hydra with all the fixings (fan kit and 3 fans). I am in the process of seasoning my humidor but the calibration on my Hydra seems to be way off. Since it is to big to fit into a bag or container I decided to calibrate my digital hydro (the small rectangle one with adjustments) and I have another digital hydro. Both will read 63% in the humi but sometimes the Hydra is as much as 9% higher, I have adjusted the calibration knob all the way down to as low as it will go. I say sometimes because when the RH reaches about 70% according to my 2 stand alone hydros the Hydra is only 2% off. The room I have them in is about 64F. I have all the beads in there charged and 2 dishes of DS water with sponges as well. I have taken everything out and just left the Hydra and standalones in there with the same effect of not having matching RH. I really think humidity sensor on the Hydra is busted. Can I take the Hydra apart to further adjust it (is it a potentiometer)? I'm still troubleshooting to find the most likely issue but can anyone offer any help?