I'd personally concentrate my efforts on getting that cable out of there and replacing it. It's flat cable, right? If it went in, it will come out, but you may need to coax it. I'll bet dollars to donuts that if you take a cordless drill and grab the cable on one end, and then start twisting it as you tug, you'll be able to turn that cable into a helix and give yourself enough clearance to pull it out without too much trouble. Grab a leftover piece of cable and conduit, shove it in there, and the try it and see if it comes. I'll bet that it does. Maybe you'll just end up with a knotted up cable and you'll have to dig it out. I'd take it, though. I like to do it once and do it right.