First of all, you shouldn't have the mainspring under full tension with the sideplate off. This puts undo stress on the hammer stud because it lacks the support of the sideplate.

Have you checked the position and integrity of the trigger lever inside the trigger? Is it still pinned properly in place? Is the lever bent?

The tip of the lever should be crowned or rounded so that it will cam properly inside the cavity in the rebound slide. I would also check for debris inside the lever cavity. (right below the alignment tab that sticks out of the front of the rebound) Take the hammer out and see if the rebound slide and trigger cycle properly without the hammer in place.

Your other post you stated the rebound spring had been altered. If the rebound spring has been cut (shortened), the new spring you ordered should fix the issue.

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Ret. LE, FA Instr, S&W Armorer