The sear spring shown in the link in Post #4 is a (Clark?) 4 leaf spring. Here's what a standard 3 leaf (center leaf not split) sear spring looks like when properly installed with the slide off and hammer down:
When installing the new one, put the bottom tab in its frame slot, lay the upper leafs down on top of everything - and then slide the mainspring housing in about half way to keep the spring in place.
When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]