The door is not faulty (really, there are no active components on it *to* go bad - the door just has two injection-molded plastic switches which perform as actuators to engage/disengage switches-- the only way they'd "go bad" is if they snapped off).
There are three switches- the primary, secondary, and interlock - and one of them has gone bad. You can use the diode mode on a standard multimeter to test which one it is. For my GE XL1800 it was the Omron V-15-2C26-K which I picked up from Mouser for 2.50$. This seems to be the common component that fails on most models. (The failure mode is the switch's spring steel retainer keeping it NO/NC loses it's elasticity for those who are curious). If you don't have a DMM to test the relay, $2.50 from Mouser/Digikey/whatever is a gamble I'd be willing to take.
http://www.microtechfactoryservice.com/switch.html seems to have more information. I didn't read through it but it had "discharge caps" in their preamble so the rest of the page likely has relevant safety precautions.