I personally wouldn't waste time replacing the switch on that light. As many of us know, it's generally a lousy light anyway.
Instead, buy a nice LED light. The one I have can switch from white to red and, being an LED, it is shock proof, consumes low energy and will outlast me. There are many good choices out there.
As to the spreader lights, I wired mine to an unused switch on the panel next to my helm. So, my dome light and spreader lights now operate on different switches. Problem solved (and simplified).