Could be anything - one area that fails quite often is the attachment of the power cord - constant tugging with enthusiastic use over the years weakens the wires in the plug and at the machine end - anywhere where the power cord makes a tight bend is an area of weakness too - sometimes the conductors part inside the insulation.
Might be the on/off switch - a cover interlock if the machine has one - could be a failed overheat cut out switch fitted close to the motor. Motor itself may have died or the motor brushes. Unlikely to be a fault with the internal wiring.
Good luck...
Peccavi, October 2009
