  We investigate the coupling between individual tubes in a rope of single-wall
carbon nanotubes using four probe resistance measurements. By introducing
defects through the controlled sputtering of the rope we generate a strong
non-monotonic temperature dependence of the four terminal resistance. This
behavior reflects the interplay between localization in the intentionally
damaged tubes and coupling to undamaged tubes in the same rope. Using a simple
model we obtain the coherence length and the coupling resistance. The coupling
mechanism is argued to involve direct tunneling between tubes.
