It could also be the main switch contacts which are the problem. Mine had nearly melted away from 22 years of use and electric erosion. Braun no longer keeps spares for this machine, so the only (very temporary) fix is to rebuild the contact wire with some solder and 1.5 sq mm copper wire. Unfortunately, it will erode quickly.
No special tools are needed, but it is fiddly. Removing the main switch cover requires quite a lot of strength and it's easy to break the plastic. Lever it away from underneath using a medium-sized flat blade screwdriver (there's a small notch in the switch cover to facilitate insertion), then remove the two phillips screws. On my model there is a small plastic cover in the corner, flush with the top, hiding a third screw, which also needs to come off.
Once the three screws have been removed, it is possible to lift the plastic cover - it's a tight fit. Note carefully how the safety interlock and spring are positioned.
Once you get at this point, if the culprit is the variable resistor, you'll see that it is quite evidently burned out. If the VR is still white and with no obvious signs of overheating, then look at the switch.
Open the main switch casing by using a small screwdriver and levering off the sides; if the inside of the casing is blackened out, it's the contacts that have been sparking too much.
If this is clean, check the other components and the underside of the PCB for signs of heating or cracking/peeling away.
Repair/replace and refit everything.
It's unlikely to be any of the wiring in the motor case - there is nothing mechanical/subject to wear except the motor itself (but that seems to work, from what you say).
Coyote, December 2009
