Abstract: Apparatus for controlling movement of a tether in a conduit is disclosed, the apparatus being comprised of a winch, two braking systems, a pair of extensible stabilizer bars and a crossbar for engaging an opening. The winch is engine-driven and mounted on a frame having wheels. Engine power is delivered through a dog clutch to a cable spool through a reduction sprocket set. A brake control arm having a friction pad positioned thereupon to bear against the spool and having a hand grip connected to a drum brake in the drive train is provided. A power arm operable to control the dog clutch and including a throttle tab is also provided. A level winding arm is positioned to be swept across the spool for even cable storage. A pair of stabilizer bars are extensible from the frame and have screw jacks at their ends which mate with a crossbar adapted to engage an opening such as a manhole. The screw jacks are operable to bias the apparatus' weight against the crossbar.