generally speaking a stock bike will not eat yours second gear unless something is broken or out of line... a clean running bike thats modded goes pretty much hand and hand with that... they simply do not have the power to chew the gears off.. only way that gear is getting f'ed is because of something breaking or bad maintnance and rider abuse...
it only does it in 2nd gear correct? if so its very likley its trashed... maybe putting a full load on it and slamming in 2nd to rip out of those holes finally took its toll on it...
Edit:just curiouse what kind of tranny oil you using and how much?