-have you tried inserting the end of the 4"/Spray-wand via associated aerosol-can of a good (hence not WD-40) penetrating-oil such as "LiquidWrench"(turquoise color can), and sending-in a big amount of the stuff best you are able; --wait a day for it to react chemically, then see if you can manage to work the cable free by fully releasing the handbrake and placing a ViceGrip on the cable and work the cable relentlessly push/pull-fashion. Naturally be sure to place jackstands under the axles or frame whenever you get-out & under!!! [knew a guy who had one of those classic '57/Cadillac-Brohem's (handmade with s/s-roof), who had pumped-up the air-ride suspension so's he could crawl-under and check the univ.joints, --well fatally, he inadvertantly pulled-off an airline, whereby the heavy car simply lowered upon his chest preventing his possibly calling-out for help!.....-R.I.P.]