Broken gear tooth

Have found my Mainshaft 25T sleeve has a tooth broken off, I have seen a few old Layshaft top gears with teeth missing, but this seems unusual.
If you can see the fracture site, is there any indication why it might have failed ?

Hi John has it done a lot of miles?
is it an old gear? or a new(modern tech) recently made gear?

Perhaps just unlucky?

Regards Mike

Hi John
Any half engineer could look at this and tell what is wrong, !

for some reason its always this gear and not the other press on gear that loses its teeth, but getting back to this, could be two things

1)faulty manufacture I would say (HT or wrong MATERIAL SPEC) - I plumb for wrong material spec first - then the HT process".
from memory your in Newzeland so what do these jokers know about engineering!! "sheep shaggers" well thats another / different story.!

2) your suspension is set up "too soft" and with too much travel under braking the bike yars forwards as you take the brakes off loads this gear with your 16 stone (if it was this, I would normally have expected to see the loss of more teeth though).

John I have been playing with that gear chart I thnk I have found the way you set up this box in order that it works better than the std CR box.! PM me I will forward a small change to one std gear.

all the very best

kind regards Derek Betts