Either the bearing block for cutter head has buildup inside or it is going bad. Try to flush out the bearing with alcohol. Take a syringe and gently squirt alcohol into either side, top and bottom, while moving the cutter head back and forth a small amount to try to remove any buildup internally. When finished, blow it out with air to dry. Once dry, put some oil next to the block on both sides and top and bottom and work the cutter head back and forth to get oil back into the bearings. Clean up the excess oil from the rail and see if that does the trick. If that doesn't fix it, the bearing is likely shot. Reach out to damonCA21 here on the forum. Last I knew, he had some of these bearing blocks. If you do end up having to replace the bearing block and need assistance, I can provide phone support.