The NOSSCR website has a new feature that is very useful. The site has a set of Google "search boxes," each focused only on the SSA website, or the Social Security Act, or the Regulations, or the Rulings, or the HALLEX, or the POMS, or Google Scholar. Take a look.
This is a very handy tool, particularly for the searching the HALLEX or POMS, both of which have terrible indexes that make finding a particular provision difficult. With search, it is easy. Go ahead and type "good cause" in the POMS search box. You will find exactly what you need.