I have a trek 7.2 Fx I use for daily commuting and a little while back the saddle started twisting on it. I thought it was the seat tube that was loose and tightened it but the problem didn't go away. Anyway today I was messing around with it trying to find a way to tighten the saddle onto the tube and the top mounting section of the seat tube just popped right off (the whole top of the seat tube that holds the saddle.) I cant find any kind of clamp or mounting mechanism and it fits back onto the seat post but is very loose and just twists around on the tube.
Hope that makes it clear, I could take a picture if that would help. Any ideas on how to fix this?