B&M 250 Blower
 

I opened the back plate and it appears the rotors have warn two circle groves into the back plate cover. The bearings are together but might be ready to be changed. It runs great I was just checking things out and noticed the grove. I opened the back plate and it appears the rotors have warn groves into the back cover plate. Anyways any ideas on why this is worn? Any tricks to replacing the rear bearings? Has this issue happened to anyone else?
Thanks

Look like rotor to plate clearance was too tight, you can adjust this clearance with diferent plate to casse gasket thicknes.
I dont have the exact spec but if i remember right you need arond min .016'' front and arond min .018'' rear plate to rotor clearance.

Hope thats help.

Call Ron Hayes at The Blower Shop. Happened to mine and he rebuilt them