A friend told me that his family will kasher his microwave in general (ie if non-kosher food was heated up in it) but will not kasher it for Pesach, letting it lie dormant instead. Does anyone have a souce for such a distinction? (Let's also assume the tray can be covered, so the issue is only with the microwave itself.)
I know people are generally overly machmir when it comes to chametz. I'm looking for a source for this particular distinction.