[stash247]

The hammer 'following' is almost always a sear engagement problem, and usually, poor hammer notch geometry, or metallurgy.
The grip safety, and thumb safety, are, by their function, and interaction with the trigger(grip safety), and sear, (thumb safety), seldom 'drop in' parts.
Brown, Wilson, and others have done all they can to make these parts trouble free installations, but they are working from the perspective of JMB's original, 'on the split' dimensions, not the working toleranced dimensions of several dozen aftermarket manufacturers. Accordingly, some gunsmithing is often required, for proper functioning.
Brownell's #59 catalog is out. Get one. They offer several DVD's, and VCR's, on, basically, 'How it works', for the 1911. How can one make a malfunctioning machine function correctly, without first understanding how it is supposed to function?
This pistol was designed, and built, by an old but clever guy, using a lead pencil, and a file, with an exceptionally good knowledge of geometry, but it ain't rocket science, just, good geometry, that makes it run!
WARNING: An increase in knowledge, on your part may bring on a perceived 'need' for more tooling, parts, or weapons. This is a common side effect. Also observed are an increase in ammunition consumption, and a burning desire for greater accuracy; these are relatively harmless, and normal side effects!