We investigate the coupling between individual tubes in a rope of single-wa
ll carbon nanotubes using four probe resistance measurements. By introducin
g defects through the controlled sputtering of the rope we generate a stron
g nonmonotonic 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 sim
ple model we obtain the coherence length and the coupling. resistance. The
coupling mechanism is argued to involve direct tunneling between tubes.