Have you had equipment failure on a trip and how did you handle it? Did you have a repair kit or did you have to improvise? What did you learn? Here are a few of mine.

Failure: hole in down, feathers flying!
Fix: duct tape
Lesson learned: do not wander through stickery brush in a down jacket

Failure: pack strap broke
Fix: lots of parachute cord and lots of knots
Lesson learned: check pack straps before the trip!

Various clothing failures: broken zipper, rip in pants, button lost
Fix: sewed up jacket so that it became an anorak, moleskin works amazingly well for holes in pants, sewed on button
Lesson learned: ALWAYS carry needle and thread, a spare button, a few safety pins

Failure: tent leak at ridgeline
Fix: regularly sponge up water
Lesson learned: should have seam sealed the ridge line, bring a small tube of seam seal

Failure: blew up a SnoPeak stove, probably cross threaded cannister when I put it on- gas leaked out
Fix: none, thankfully with a group so shared their stove
Lesson learned: blowing up a stove is not cool. Luckily none of us got hit by the shrapnal. I am now very careful when I screw on the cannister to the stove.

Failure: flat Therma-rest
Fix; put up with it
Lesson learned: Do not tie thermarest on back of pack when bushwhaking. I also now take a short section of blue pad wtih me as back up.