Based on your description on the blinding, it doesn't sound like a timing problem. What I suspected is that the cylinder stop didn't clear the cylinder recess before it started to rotate, in which case the blinding would be felt at the beginning of the rotation, so much so that the cylinder wouldn't even rotate at all.
The cylinder rotates counter-clock-wise from shooter's perspective. Hammer pulls back, cylinder stop clears, hand pushes cylinder, cylinder rotates, somewhere half way through the cylinder pops up and drag on the cylinder, it engages the next recess and stop the cylinder, hammer drops. Make sure there is no burrs or irregularities on the cylinder, where the cylinder stop drags on.
If all is fine, It is then likely due to irregularity on the ratchet pad (the star) as suggested by other members. Mark the ratchet point responsible for the blinding chamber and compare with the other 5. At the beginning of the rotation, the hand pushes under that ratchet point. As it progresses, the ratchet point slips to the left of the hand. The tip of the hand slides along the ratchet point. If there is burrs the hand will catch it and cause blinding.
-TL
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