I recently ordered this, and it just arrived a couple days ago. So my heat control knob does not go down on the shaft all the way. I pressed as hard as I could, and even though it gets in relatively close, when I twist it, the shaft does not twist at all. There is some weird plastic in the inside of the knob as you can see in the image, is that the issue? I tried sanding it down, and even getting the knob down further, the shaft does not turn in response. It budges a tiny bit, but is just not moving. What should I do? Get in contact with the manufacturers?