I noticed one thing during my replacement that may affect others doing this repair. Upon reaching step 30 I noticed that my volume button bracket appeared to be bent slightly near the lower screw (the one toward the bottom of the case). Ultimately I had to bend the bracket to make the volume button work correctly. When I reassembled the bracket with the new buttons before bending it the - button would not come back fully to its normal position. After careful bending with a pair of needle nose pliers and the button worked correctly.

It is CRITICAL that you test your volume buttons and the ringer switch before you reassemble your phone!