It can be a real pain in the butt getting the spring inside, i always struggled. Gotta keep trying and trying. Use some needle to try keep it in place when you close the nub. It's gotta be in the middle and as you close the nub, the spring should expand and slide into place... i know it sounds easy but it's not. Like i said it's not easy so just gotta keep trying. Watch out though, don't stretch the spring out.