The missing spring on the cylinder hand will cause the hand to fail to extend into the ratchet teeth on the rear of the cylinder.
This may cause the cylinder to fail to rotate as the hammer is cocked.
It also can contribute to the cylinder turning further than it should but that is not its primary function.
The Cylinder Stop, which protrudes upward from below the cylinder is the part that keeps the cylinder from spinning and locks it into position prior to firing.
This Cylinder Stop is spring loaded to cause it to rise and engage the cylinder slots.
If the spring that lifts it has broken, that would be the primary reason the cylinder continues to turn.
The Trigger & Stop spring is a 2 legged flat spring and their breaking is quite common.
As a side note, when you slowly cock your pistol the following things should happen.
(As you check these out, look thru the gap between the cylinder and the lower part of the frame.)
1. Raising the hammer about 1/8-1/4 inch from the fired position will lower the cylinder stop, disengaging it from the cylinder.
The protruding end of the stop should completely disappear into the lower frame. There will be no sound.
2. Raising the hammer slightly further, the hand will engage the cylinder ratchet teeth and the cylinder will begin to rotate.
As the cylinder begins to rotate you should hear the "click" of the sear falling into the half cock notch.
3.Pulling the hammer further back, you should see the cylinder stop pop up out of the lower part of the frame. This will cause a "click" as it hits the cylinder.
4. Bringing the hammer further back may cause two clicks to be heard.
One of them is the cylinder stop falling into the notch on the cylinder. The other click is the sear entering the full cock notch.
If the cylinder hand fell to its full depth in the cylinder slot in #3, only the click of the sear entering the full cock notch will be heard.
If you put your thumb on the hammer and squeeze the trigger, the hammer should fall without causing the cylinder stop to move. Some guns will make a faint sound as a arm on the cylinder stop slips over the cam on the hammer that actuates it during the next cocking of the gun.
If you remove the brass trigger guard, you will see the 2 legged flat spring that actuates the trigger and the cylinder stop.
This spring can be installed upside down and if it is, it won't operate the cylinder stop as it should.
As your cylinder stop seems to not be working, if the two legs on that spring are unbroken, try removing it and turning it over. Then, retighten the screw that holds it in place and reinstall the trigger guard.
If you do this, try your gun again.
The cylinder stop may snap up like it is supposed to do and your problems are solved (except for the spring on the hand).
Speaking of the spring on the hand, its job is to push the hand out of the slot in the recoil shield.
Some have found that by clipping off a "bobby pin" (flat hairpin) and working a short 1/2-5/8 long piece of it into the small slot in the hand that it will fix the problem without your having to buy a new part. Some people solder it in place but others have found that lightly tapping the hand to collapse the slot onto the new spring will be sufficient to hold it.
