Could be that it was just a fluke, my fault or bad luck, but I will never buy TKO bearing again. My rear ceramic bearing felt notchy out of the bag. I installed it anyway with the Novarossi extraction and mounting tools following TKO's instructions. Ran the engine for 5 tanks, then it seized and the engine was totally destroyed. Dismantled it and found a broken ceramic ball of the rear bearing. Next time I will buy Novarossi...