First step would be identifying which side of the switch it is on (cord side or motor side).
With the switch off and the cord unplugged, put an ohm meter or simple continuity tester of some type across the plug terminals.
If you get a reading of continuity with the switch off then the problem is in the cord or the switch itself. If you don't the problem is on the other (motor) side of the switch (or less likely the switch itself). A cord or switch is a pretty easy fix, anything beyond that gets a bit more involved but not excessively so. Disassembly of something to get at the wiring to check or fix it is going to be needed in any case, test first and disassemble as little as possible. Keep the thing fully reassembled to check the fix with line voltage to see if it works, not a fix and check before putting everything back together with any bare electrical stuff exposed (assume anything that can go wrong will go wrong).
