Model520fan is correct the hammer stud hole in the sideplate was the problem on the NY-1 Model 60's S&W inspected each of the guns at the range and if the gun was found to be within spec they stamped the inside of the frame above the yoke with a silhoutte target.

If your gun has that stamp above the NY-1 than it was one of the guns that was in the NYPD inventory. Before the changeover to the new forum R.M. Vivas has a great article on the S&W NY-1 Model 60's but I can't seem to locate it.

Hope this helps..........and FYI The NY-1 Model 60 was replaced with the S&W 640 which were not marked NY-1 on the guyn itself.