"Every once in a while it makes a hell of a fuss and sounds and looks like an arc welder."

Kendall, are you putting metal in the microwave? Tea bag staples, dishes with gold or silver trim? Forks? Spoons?

If not, then I advocate that you ditch that microwave before it starts a fire or gives somebody a shock. It will be well worth the small amount of money that waves cost nowadays.
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The DH and I get a lot of use out of our $100 microwave - cooking vegetables, thawing things, sanitizing sponges. I wouldn't want to be without one.