My guess is a cable. I haven't had time to take it to a shop yet, but I don't intend to wait on that. I took the car to a shop a couple of years ago because all the staples were pulling out of the rear curtain. I got some good advice from the owner, although I wasn't ready to act on it at the time. Now that circumstances have essentially forced my hand, I'll be heading back there, as I got the sense he was giving me fair estimate and an honest assessment. I'll be replacing top as I also noticed a small split in the vinyl when I got the top up. It's only about an inch long, but it will only get bigger with time. Not doing the duct tape thing, even though I have a black roll on hand.