Having a self contained spring reel reduced it to just a couple hall effect sensors & a pot.

Magnets are hot glued in.

Hall effect sensors are glued in.  This arrangement gives direction & quarter turn accuracy.  The lion kingdom highly desires a more reproducible method of farstening hall effect sensors.  A more compact adhesive would get most of the way.  Most modern sensors are soldered on a board & the board is put in.

A test fitting on the robot showed it meeting the requirements for tension & steering.  It would ideally be down near the wheels but it's going to require a new front panel. 

  Using a prebuilt leash part means discarding a lot of parts intended for an animal, but lions discard a lot of ball point pens to get the springs.