make sure the wear blade just misses the casting on the front, this shears trash so it don't get into bearing area. probably has too many washers between bearing and rotor on shaft.
not hard at all. take middle concave out and put asoft 2 by4 under the front of the rotor an top of front concave then tighten up concave to suspend rotor. take 7 bolts out and the stud in the center of shaft remove front crossbar and remove bearing , reinstall in reverse order.