I have had my Hova-bator running for about a week now and not once has it gotten to 37.5. The first three days I could not get it below 39 degrees. I had the wafer thing twisted down as far as it could. And now it wont go above 35. I keep turning/twisting it up until the light turns on, leave it a few hours, then come back and its STILL below 35. \ Whats going on? is it broken or and I doing something wrong?