Before you do anything else - cut away the mains plug and a few inches of cable and fit a new plug - the cost is minimal and it only takes a few minutes.
An internal wiring fault is highly unlikely - a broken wire inside the cable at the plug end is very common from constant tugging over time - I have repaired perhaps 20 vacuum cleaners this way.
Good Luck...
November 2015
howtomendit.com for free repair help, information and advice.
