High resistance

If you do not have an ohmmeter or an expensive specialist body wire meter that shows the resistance, a careful visual inspection can often reveal the fault. Examine the section close to the plugs.  Sometimes there may be green or black patches on the wire under the insulating sleeve. This is probably corrosion caused by sweaty fencers, and may cause either high resistance or a complete break. This section should be replaced if faulty.

If the wire looks clean and in good condition, and no break is visible even under tension the fault probably isn't there, and you should check the screws in the plug.