Sorry I've never opened an Abu up. Also searched AlanTani's site, no info!
Get yourself the Reel schematics, and go for it. Take photo's at every stage along the way, so that you can put it back together again properly. (and then make a proper service tutorial afterwards!!

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Otherwise take it to Craig Neil CDS Angling, in Centurion and let him do it for you.
Good luck!