whenever wife runs vacuum cleaner for about 10 minutes, the prongs on the plug get hot. the cord itself does not heat up. this happens all through the house, not just at one outlet, and no other plugs or cords heat up.
is this normal, or should i be concerened about this?
note: cord was run over once - sheathing was torn up a little, maybe a nick or two on insulstion on individual wires inside. i wrapped each wire with vinyl electrical tape & the wrapped entire cord at that area.
should i think about replacing the cord?

thanks