I have the spring your referring too. Then the light came on,

http://www.oldchevytrucks.com/cart/product.asp?prodid=ME156&i=9879|||||

It's the brake cable with the spring inside the drum that pulls the lever, that turns the shaft, that pulls the 40 some inch rod, that pulls the E-brake peddle to vertical or some part there of.
From time to time I can't find the light switch.

Thanks for your help.