Rb6 diff maintenance

[ejw]

Will be stripping my rb6 down tonight to check a few things causing me some braking issues and while it's apart I thought I might inspect the diff.

Car was bought second hand a couple months ago and I haven't carried out much maintenance since!

Few questions:

1) is their a simple way to ascertain whether diff might need attention or not before stripping buy turning wheels or something, what should it feel/sound like? ( when I hold both wheels and turn in same direction slowly it feels very clunky)

2) when I strip it all apart are their specific things to look for other than obvious damage to balls etc?

3) if everything looks to be in good condition, should I re apply clear and black grease, and which one where ( have ae only)

4) finally can anyone suggest a good process for setting rb6 diff correctly once it's rebuilt?

Any help greatly appreciated!