If you need your gears under cut (either up or down) contact Coljen gears in victoria (google them), they are GOOD and charge the correct price, not the inflated rip-offs that some will try, they also use a machine when back cutting, all dogs still contact as they should. I have just had a look at some gears they did for me 10,000+ kilometres ago, still perfect.
I believe they will also repair and/or remake new gears if needed,shafts too from memory.
Talk to Colin or Jenny.
Kt