My lad bought a second hand, stand alone, dishwasher from an auction site. One old lady owner, hardly used, in good condition! Just recently he has noticed that when its done its job and he opens the door and he touches anything metallic inside(like the door internal cover or basket) he gets a tingle or minor shock. I have checked the plug to ensure there are no stray wires and all is ok. It is a Hotpoint Aquarius model no. SDW60 Before I start pulling it out to try and check the wiring is there anything obvious to go to with this model?