Dave, I can't do that wrote:
Hi people,

I have an old HF 4" x 36" belt sander that has provided probably 12
years of reliable service. This afternoon, just when I really needed
it, smoke escaped from the switch at turn on.

Does it look like:
http://www.harborfreight.com/manuals...3999/93981.pdf

You could order a replacement switch:
1-800-444-3353

Prepare to wait ~30 - 45 days.

--Winston