I agree about that upper thread tension assembly being scary and complicated to take apart when you first look at the diagrams. I was very afraid to try it. BUT, if you dive in and take it apart and put it back together a bunch of times, it gets easier and easier. Its not so scary after you do it a couple of times. I had to take apart a rusty tension assembly on a 15-90 and clean it all up. It took me several tries to get it back together and get the number dial to line up right, but with the help of that old manual with the blown apart diagram it works like a dream. If your afraid to work on this yourself, don't be. Dive in, you have nothing to lose and everything to learn. You might surprise yourself.