Rear shock play

I ride a Trance X Advance 2012 with an RP23 shock that has now developed some play in the top mounting bolt. I suspect the 2000kms it's done has worn the silver things that insert into the eye of the shock and they need replacing. As you can probably tell by reading this I have no mechanical aptitude what so ever and have had to learn maintenance as I go. Anyone know the name of the parts I am referring to and where I can get replacements from? Also, do they need to be pressed in tight with a special tool or does the bolt tighten them up sufficiently?