Your hand is no doubt worn down, causing the cylinder to fail to fully lock into place before the hammer reaches full ####, probably even if the hammer is drawn back as far as it will go.
The best solution is to replace the hand and stone the surfaces that contact the ratchet carefully if the cylinder locks up before reaching full ####.
(The opposite of your present timing problem)
Marstar sells a Pietta parts kit for the 1851 Navy/1860 Army for $32.42, which includes all of the springs, bolt, hammer, trigger, etc.
(Everything but the screws, which is a separate kit that they also sell).
It's the same parts kit for both the 1851 and the 1860, since the Colt 1860 used the same cylinder frame and parts as the 1851.
When stronger Bessemer steel became cheaply available, Colt simply notched the frame and used a stepped, increased diameter cylinder to allow him to create a smaller .44 than the Dragoon. (With a new barrel design, longer grip straps, and a longer grip.)
A second possibility that you could try is to elongate the hand by center-punching it on both sides, above the pivot point but below the working end. (in the center). Since the hand is pretty soft, and only case-hardened, a punch indentation at the same place on both sides will make it slightly longer. If this distorts the faces of the hand, you can tap them flat with a 4 oz. or 8 oz. ball pein hammer. You don't see the hand because it is hidden inside, and it just might be enough to last for quite a while.
I have found with my Pietta Remington that a natural grease lubricant made from olive oil and beeswax works very well to stop fouling from tying up cylinder rotation. I use it on the cylinder pin (arbor in your case) and also as grease over the chambers. Instead of dry fouling, you get a softer greasy fouling that is easilly wiped away. Also, the lube gets blasted into the places that the dry fouling usually goes. I shot about 24 shots last time out, and only wiped off the cylinder faces and base pin when I reloaded. With the Colt arbor and grease grooves this lube should exclude fouling well enough without having to knock out the wedge too frequently for wiping down the arbor.