The lines are held together by a cicular spring. You need to got to an auto parts store and explain what you're doing and they'll be able to sell you a set of spring expanders for around $30. There's a multi size tool also available that's alot cheeper but you don't have much room to work with and I think the individual rings are better. They're a little tricky to use. You have to select the correct size and press it into the fitting so that the spring is expanded enough to pull out the flared tubing. You have to push the tool in and hold it and at the same time pull the two pieces of tubing apart. Good luck.... They go back together alot easier. Be sure to replace the o-rings.