Hi,
For me, I never have problem with gears, even the old ones. They all perfectly no wears at all.
Ey that's a very usefull answer
To prevent those gears from wearing you should make sure they are perfectly clean.
Then make sure they are put in the right way, so the gears fit perfectly.
After that you can oil them.
Let the car run on a bench, so the wheels do not contact the floor.
After a few packs open up the gearbox, and re-oil the gears.
Then run the car like you do normally.
This should do the trick.
Thomas