I am installing my pellet stove today and ran into a little issue I need help with. I came off the back of the stove with a 4" T cleanout, and then into a 36" piece of straight pipe, and than a 90 elbow that I am trying to fit into an adapeter to my 8" MetalBestos Chimney adapter. The issue is that the elbow is about a half inch short of reaching the 8" adapter. What is the recommended way to make this work?