Would rounded off teeth on Y1 JDM 3rd gear tranny make the 3rd gear grind, even with brand new selector and brass synchro?

I have big tranny headaches, need some help!

 

it depends on how bad the gear is rounded, they are supposed to have sharp edges to allow the gears to catch each other better.

 

Well, they looked pretty messed up the last time I opened up the transmission. Everything in the tranny seems to be fine, other than the 3rd gear syncro teeth. I just want to make sure this is the problem before trying to replace it.