The 510 in the REO was changed to be adjustable a short while back to be able to adjust the height of the pin to accommodate an atty with a 510 connection that is not of normal tolerances. If you post a pic of the top of the
device without an atty, we would be able to tell if it has the new or the old 510 in it...
Here is a pic of both... The new is on the left side. There is a left hand
threaded set screw in the center of the 510 to adjust it.