liner wants to drop - need advice

keeping this as short as possible: i installed 35' flex liner (6" round) from bottom up, got so jammed from insulating blanket or wire mesh sleeve (with 6' left to go) wouldn't go up/down. Had metal worker craft a 10' section of rigid pipe, with taper to 7" at bottom - i slid it down over the liner end like a sleeve. Mounted top cap. Now, 2 weeks later, the liner is wanting to drop down when i work it from the firebox (pre-stove install of course). Am i screwed? any advice?