Same happened to me. It ended up being the switch itself. The inside of the switch was gummed up with 30 yr old grease and the metal was not making contact. Cleaned it up and epoxyed it back together(plastic case cracked while trying to disassemble. Pretty simple and saved the cost of a new 2 speed switch which is $150+. Be sure to mark the back of the switch with the correct wire colors(If I remember 5 of them).
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