The cable is held in the housing by a flat-sided stud, when you tighten the stud's nut the flat side wedges the cable in the housing. If you loosen the nut and drive the stud too far into the housing the stud will wedge the cable again so the trick is to loosen the nut and tap the stud forward just enough to loosen the cable.
Once the cable is loose in the housing, remove the allen head pipe plug on the bottom of the housing (you'll lose some fluid). With the plug removed, reach up into the housing with a common screwdriver and feel around for the retaining wire, push up on the wire to release the cable from the unit.
