On Wednesday, November 28, 2018 at 3:14:06 PM UTC-5, Bruce wrote:
Need a replacement switch for my circular saw. Does anyone know of a
replacement for that original switch, number 843156 (or 876341?), or a source
for it?


You mean something like this source?

https://www.toolpartsdirect.com/rock...cular-saw.html

Illustration Item 4 - 876341 - SWITCH - $27.43

Google - Coming to a town near you soon! ;-)