I would definitely try to rebuild the teeth with a tig then re cut the gear tooth profile.
First I would also be looking at the wear in the blade hinge, and the possibility of re bushing along with new pins .

Kryspen said..
I pulled our my folding prop as i have noticeable out of balance spin. The bronze tooths are worn out and not mashing together.
The prop had small red spots and apparently is not possible to weld build teeth.
Is really that so ?
Do anything have ideas on how to fix the teeth on folding prop ?
Unfortunately they don't make this prop anymore and is not possible to get new blades ( 120 S sail drive ).

120 S is a very common leg.
Any propulsion engineering shop should be able to get you a new prop if not the part.
Folding props have a very limited life.

Not all folding props have the gear teeth. The gears just mean the blades open the same. The Gori two blader has blades that open independently. I would suggest trying to balance the blades and see if that fixes the out of balance. It sounds to me like one blade is opening further than the other one. This is more easily fixed than trying to get the gears to mesh. The red spots sound like electrolysis from not keeping up with anode changes with a sail drive. gadsolutions.biz/marine-corrosion/propeller-corrosion
This can be serious and the blades can be severely weakened. A few red spots are OK but if it all goes pink the blades can fall off.