Hi!

Ancient and honorable Amana RadarRange.

I'm not sure you can even wear these out, for the most part. :-) Well, those
and Litton ovens.

Found one paddle fused: http://tinyurl.com/2t66ud

My guess is that some gunk built up on it and finally resulted in its
getting "microwaved". You might be able to clean it up and use what's left
without further incident. Left alone for long enough, this might prove fatal
to the magnetron, but I think you've caught it in time and could still fix
it.

There have been some other comments on metal in microwave ovens, and how
certain arrangements or types can cause problems. I have a Sanyo microwave
oven from the 1980s that came with a large metal (wire bars) shelf to allow
the use of two plates in the oven at once. It works well and has never shown
any sign of arcing.

William