Why radient toaster continues operation?

You will have to dismantle the toaster for this one. It really IS a job for a competent appliance repairman.
These toasters are GREAT and very repairable.
Apart from physical damage or a blown element, most repairs are only minor adjustments or cleaning contacts.
This fault is the contact toggle mechanism (operated by that "W" shaped wire in the "one slice only" side) is jamming. Possibly by a peice of crumb etc.
You could try a good clean (take the toaster outside and invert it. Shake vigourously).

Jeff
December 2009