Our Gleaner auger was worn out quickly as well, replaced with a chromed unit(not polished).
After 800 acres of corn and beans it looks the same as new, dont ever plan on replacing it.
Sounds like you need a new one if it is already serrated, but take the new one to a chrome shop, have it stripped and chromed and you will replace everything around it first...
Your up auger in the tank? Take it out while it is still good and do the same, these two augers do a ton of work..
Good luck