My sister has a Whirlpool electric dryer (Whirlpool makes Kenmore laundry machines for Sears).
She was starting to get shocks from her dryer. It turns out that one of the wires that go down to the stuff below the tumbler inside the machine was rubbing on the exterior of the tumbler. Eventually friction wore the plastic insulation off the wire, and the bare copper conductor came into contact with the metal drum so that you could get a shock from the tumbler if you opened the dryer door.
You should be able to buy a Whirlpool dryer service manual at any applicance parts store. I'd take the model number of the dryer down to any appliance parts store and they'd be able to tell you who made the dryer. Buy a service manual for that make of dryer and take the front panel off the dryer and look for any wires that could be rubbing against the tumbler.
If your dryer i the same model as hers, they're a breeze to repair.