SDS Drill Chuck - Lost the whatever that holds the drill in place?

I was using my drill in hammer mode when the whole chuck assembly fell apart. I now realise that this was due to the circlip, that holds the assembly in place, coming out of it's slot. Unfortunately, when the sliding collar come off I lost the ball bearings, or whatever, in the rubble I had created and didn't relaise it until I had cleared thr rubble away and started to reassemble the SDS chuck.
Does anyone know what the sliding collar hold in place and I it is possible to buy replacements?