Faq II: Equipment & Maintenance:

2.10 Points & Blade Wires

     Many fencers have experienced trouble mixing their points,
     barrels, and wires.  They are best used in matched sets.

     Points are regularly tested in competition.  Both foil and epee
     points must pass a weight test, by lifting a mass (500g for foil;
     750g for epee) after the point is depressed.  (Technically, epees
     only have to lift the mass 0.5 mm, whereas foils must lift it to
     the top of the point travel.)  In addition, epees must pass two
     shim tests, the first to make sure that there is at least 1.5 mm
     of travel in the tip, and the second to make sure that the point
     doesn't light until the last 0.5 mm.

     If the weight test fails, the main spring can be replaced or made
     heavier by lightly stretching it.  If the fencer thinks his point
     is too heavy, the spring can be replaced, compressed, or softened
     by heating one end in a flame.

     If the epee 0.5 mm shim test fails, the secondary contact spring
     is too long.  It should be adjusted or compressed.  If the 1.5 mm
     shim test fails, your point may be improperly set up, or may be
     mismatched with the barrel.

     Most points are held together by a pair of screws on the side of
     the barrel, and adjusting the springs requires disassembly.  Some
     (Italian) epee points are externally adjustable using a small
     wrench.

     FIE epee points use a solid contact in place of the secondary
     spring.

     Epee points work by closing the circuit between the two blade
     wires when they are depressed.  Dirty or faulty points will
     normally cause the weapon to fail to register touches.  Foil
     points work in the opposite manner, by opening a closed circuit
     between the blade wire and blade.  Dirty or faulty points will
     usually cause the weapon to produce spurious off-target lights.
     See Troubleshooting (sections 2.13, 2.14), below.
     Blade wires are typically insulated with cotton to facilitate
     gluing and cleaning.  Nevertheless, inexpensive wires can be made
     at home using plastic-coated wire-wrap wire from an electronics
     store.  Use the cup from an old wire, and attach the new wire by
     heating the solder connection with a soldering iron, or crimping
     it, as appropriate.