Product review (5 stars): Saved me from buying a new microwave!
Exactly what I needed to fix my microwave that was arching sporatically when in use.  I was ready to get a new microwave until I did some research and discovered this as the possible problem.  No more arching when I replaced this.  I have ordered two and have a spare on hand now.  They do get dirty very easily which is what caused the problem.