wed5530 dryer. (whirlpool)

I put a load of clothes in and it will take a couple of hours to dry them. I checked the heating element and it comes on but it looks like only a partially (looking through a mirror while it's mounted, but if I remove the element from the heating tube and turn the dryer on, all of the element glows a bright orange. what would cause this? What else should I be looking for. It heats up, but just takes forever to dry. I was under the impression that the element is either on or off.

I took the shoot off where the lint screen goes and found no obstruction and flow to the outside is good. I'm still curious as to why that element works differently when it's away from the housing and by it self. Is it a grounding issue that causes this? I'm not thrilled about buying a new heating element if I don't have to.

I had checked the airflow in the dryer and why would you need to check the short distance from the inside to the outside housing with a damper. But... as it turned out, there was a shield that keeps the critters out but in this case it was full of lint. The damper will have to be enough and the shield is gone. I'm actually surprised that much lint was able to by-pass the lint screen. We don't ever run the dryer without the lint screen. Anyway... thanks for the advice. This forum works! This is the second time I've used it with success.