I really don't know, as conditions and types of grains will make a big difference. If they need replacing, I would take a look at the stainless steel vanes. Good aftermarket ones, I believe are only made by loewen.
You may want to look next to each vain and find that the cone wears down. Good suggestion is to pull the rotor and remove the vains, weld up the area and install new vains. did this on a 1660 before the cone wears thru. JWK
