Unfortunately yeah that is duct tape across it. The fins are very uneven and the airflow wasn't as good without it. I compared the thermal with and without using my flir (I do understand this isn't the most accurate method). After 20 minutes there was a 10 degree (5C) difference in favor of the tape.
And yeah, when I ultimately get tired of this ghetto look I'll get a good heatsink and blow across. I have noticed it does affect the beam, especially since we have a coal burning furnace (very dusty!)
You have a coal burning furnace, Zach? Must be an older house. I remember when I lived in Massachusetts we had an oil burning furnace that needed to be filled just before the winter started. That was in the late 50s and very early 60s. When my mother died in 76, we buried her in the family plot there and I visited that house. It was a lot smaller than I remembered it.