As a hobby I fix equipment for my fencing club and sometimes I armor at sectional and national tournaments. I've collected a few tricks I use regularly and posted them here.
On this page I have pictures of some of the tools that I have built.
Foil points, especially the German points, get corroded fairly quickly. To remove oxide buildups, I clean the mushroom contact inside the barrel with a brass tube of slightly under 1/8" in diameter. A couple of quick twists and almost all of the oxides are gone!
Most French points I've seen have a loose crimp on the tip. I heat the tip with a soldering iron, and I apply a tiny bit of solder to make the crimp whole again. If the solder leaves a projection, I file it off.
Cleaning the barrel can be accomplished with a bit of paper towel that's been rolled up. It removes most of the build-up of tip tape crud.
All of my epee points are lubricated with the Radio Shack teflon lubricant. It works really well--many "marginal" hits that normally wouldn't register set off the machine when the point has been lubricated. Be sure to tighten the tip screws otherwise the tip will fly out like a miniature cannonball.
Sometimes the cord will be fine electrically, but will still not work because the little metal "wings" on a prong have been flattened and do not make good contact with the socket. I take a small screwdriver and spread the "wings" out which solves the problem.
Here's a good body cord material--phone cord. Make sure the strain relief clamps the cable adequately.
(Thanks to Bill Hall for this neat trick.) Sewing on a patch can be really time-consuming. Here's a better technique that even results in a better patch: Take some Infinity Lamé material and cut out a square slighter larger than the broken spot. Using a hot-glue gun, make a bead along one side of the damaged part, and quickly place one side of the patch on the bead of glue and press it down. Repeat for the other three sides. Test the lame using an ohmmeter and a test weight. If the patch does not conduct on some parts, use a knife to scrape away the glue on top of the patch.