The Other Left,
Another perspective:
Because new model rugers do not need the hammer moved to the 1/2 cock position for loading/unloading, the chambers do not align with the loading gate when the cylinder is turned and the pawl clicks.
So a new "indexing pawl" (that malfunctioned in one of your Rugers) was added to the New Vaquero and a few other NM Blackhawk revolvers so that the chambers will align with the loading gate slot like the old model Rugers and Colts.
Here you can see both the cyl pawl on top and the new Indexing pawl shiny button beside it which makes the click you hear::
Once it clicks the chamber is aligned with loading gate. To make it work this way, the regular cylinder pawl (or hand) no longer touches the cyl with the hammer down and no longer clicks. It's called a "free wheeling" cyl pawl and allows the cylinder to freewheel in both directions with loading gate opened. This makes it simple to align chambers with the loading gate. The great benefit of freewheeling cylinders is that if you load a round that might have a high primer, or a round with pulled bullet from recoil or other problem that makes the cylinder too tight to turn, you don't have to pull the cylinder to unload it, just turn the cylinder in reverse and unload it thru the loading gate.
However, although the new indexing pawl (the button) aligns chambers properly, it will not allow the cylinder rotation to be reversed. Therefore you lose the advantages above of the freewheeling cylinder. By removing the indexing pawl screw, sprng and button, you regain the freewheeling cylinder. This I much prefer and find more practical in shooting the Rugers. And of course you can always re-install it at anytime.
Hope that's useful,
Jim