cnterline

I have an 03 SL 500,the ABC pump pulley has a ring on it that is spotwelded to the pulley,it broke loose on 2 out of the 3 welds and was making a racket so I removed it and re installed pulley for now,my question is can I leave it like that ? it has 2 grooves in it I suspest for balance,I was gonna tig it back together or maybe just buy a new one,the part number is on it does anyone know what purpose the ring serves ?