Hi Tonny, or is it LR? After reading a couple of other posts, I asked my wife to look through the exhaust port with a flashlight. She described it as looking like a partial eclipse....when it became a total eclipse, the two tubes were lined up! They overlap by a couple of inches, so there is no getting it wrong. It took a few tries, and could have probably been easier with someone outside using a long screwdriver to help guide the exhaust tubes together. I can envision a tool made of a slotted tube to help do this, but it really wasn't that hard.