When you say you have this issue, you mean you have the issue shown in El Mamito's post above or you know you need a new circlip like M109Rider (the original poster on this thread)? If you have the issue in El Mamito's pic, you need to figure out exactly what's broken. It could just be a crapped out circlip, but it could be like M109Rider's issue and the entire flange may be bad. Figure that part out and order either the circlip or the flange and you should be good to go.
As for how to figure it out, drain the diff, pull the cv axles, and then pull the flange that's not seated fully in your diff. Inspect it and confirm it is in good condition (not chewed up or broken) and still has the groove on the end for the circlip. If so, order the circlip and install it. If the flange is broken, order a new flange and install it.