Electrical tape didn't work. I dropped the disk and it rolled away somewhere, I couldn't find it. So I removed the EGR tube from the EGR, then I cut a piece of sheet metal (like HVAC ductwork metal) into a round disk that fit into the fluted end of the EGR tube to block it. Then I bolted the EGR tube with the disk inside it back onto the manifold. That worked fine. I'm thinking about taking it back apart, cutting the end off the tube, and reinstalling that, but who knows, maybe I'll skip it. I'm just concerned about water getting into the tube and rusting it out. But I probably won't have the car that many years anyway lol.