If like other N frames, there should be an overtravel pin inside the spring of the rebound slide.
Saw one old 29 like new due to this. Same problem.
The cut to length side of the pin was to the outer edge of the slide and it had a burr. Simple grind of bevel on edge solved it.
Could have flipped the pin, but the next poor slob that ever took it apart could have put it back in the "wrong way" and had the problem again.
Slight bevel (barely there) and the pin length was unchanged, and orientation no longer mattered (the untouched end had a radius from the factory).