looking for an obsolete part?

I have a Sears Craftsman Compound Miter Saw; 3hp; 10" blade. It is missing the button on top of the handle. I looked up the usual manual (it's item 15) and it says it is no longer available. My saw is Model No. 1132535200; Serial No. 96115P1918. Any Suggestions on where I can find this part?

Georgia
June 2012