This is the best LST diff rebuild thread ever.
http://www.losiforums.net/showthread.php?t=113
Run 15,000 fluid and HPI hardened pins under the sun gears, HD cups, HD oudrives. Follow the rebuild thread and your issues will clear up. I run my slipper really tight and with that set-up I rarely break diffs anymore. i also run my Punch controll at %80 with the castle 1800 KV.